Miss Manners has always been surprisingly modern and with it, in my experience. She’s not Emily Post. She’s given useful advice on inviting polyamorous tuples to weddings, on how to use texts in helpful ways, and when there were massive Internet fights on whether the toilet paper should go over or under the will in the front, she advised that toilet paper rolls should be changed in the privacy of your bathroom, to meet the preferences of whoever changes it.
Now that’s what I consider more real “manners,” and not the other stuff mentioned in this thread. My (already long) post originally also included stuff about there being actual practical manners that could be useful, and that it would be good if someone would help with those. Practical advice about how to kindly and politely deal with things you don’t have much experience with is a good use of manners. As is avoiding pointless fights over arbitrary things.
If, on the other hand, she had said there was a proper etiquette for which way to load toilet paper rolls, I would have rolled my eyes.
Maybe a hijack but what happens with a shared bathroom and those using it do not agree?
I have strong feelings on this (although I do not think I have engaged in any internet fights over it).
If I see someone cutting up food, I assume they’re preparing the food for their toddler.
She said whoever actually changed the roll got to decide. Which is a pretty workable solution. My husband and i don’t agree, and we decided to accept her guidance on this.
Does that lead to strategic toilet paper usage to time who changes the next roll? 
“Alleged” expert? [swoons] Miss Manners’ level of correctness and infallibility is only slightly below that of Cecil Adams.
And I suspect that many of the questions she has gotten over the years have been inspired by the asker feeling uncomfortable about something (whether their own behavior or someone else’s).
Some people are pretty good at reading social cues, at observing the behaviors and reactions of those around them and adapting their own behavior to fit in. For some people, knowing the Right Thing To Do socially is obvious, either because of how their brain works or because of what they learned so long ago they don’t remember consciously learning it. And then there are other people, who have a harder time understanding how the social world (or some part of it) works and how to fit in. For such people, it’s helpful to have rules to follow and to know what those rules are.
I remember being shocked when MM took someone to task for wearing a wristwatch–I mean this was late 20th century, not 19th. Who still carries pocket watches?
I wish you had provided a cite, or at least some more context. Instead, I was forced to google, and here is at least one of the things I found, which I think is a good sample of how Miss Manners writes:
Either that’s not the specific thing you’re remembering, or you’re not remembering completely accurately, because Miss Manners there is not taking anyone to task but rather is being asked to settle a dispute by saying what the “rule” is (and why).
Personally I have never found Miss Manners to be anything but sane and sensible, while offering an informed yet ironic window into bygone standards, why they made sense once, and why some of them still make sense. If you want to be offended by cultural mores of certain classes, I think you could find a more fitting object of your anathemas.
I’ll bet the OP is one of those people who pull the spoon toward them in the soup bowl instead of directing it away, like civilized diners do. 
How do you suspect she holds her pinky finger when she drinks her tea??
She has also addressed the question of what to do if one is pinkie-less, although she is unsure whether or not to take the question seriously:
If the food is on the dinner plate at the dining table I agree that cutting all the portions into bite sized pieces does looks infantile.
But at home I do prefer having cuts of meat pre sliced before I plate it. I just prep it in the kitchen first. To me it’s the sounds of steak knives scraping china that grates. Also it usually is eaten with a mess of salad greens anyway I just stab a hunk with the arugula and munch out.
Using a fork and knive to eat a hamburger in a restaurant seems far fetched. If it’s too big and messy to pick up and eat I’d just remove the bun and dig in with fork and knife. Probably wouldn’t order that again.
I life the spoon directly upward. And I don’t drink tea.
I eat most meals at home with chopsticks, so my presentation is often guided by this. I just made a lovely Beef&Broccoli, subbing turkey for the beef. Perfect for chopsticks.
I often cut my burgers in half. When my kids were little, I’d cut their sandwiches into halves or quarters, making things more manageable.
Turns out my kids still do this! Eating dinner with my son-in-law he had an epiphany when I cut my huge burger in half. “So that’s where she learned that!!”
I’m like Seanette. I’m right-handed, and it makes no sense to me to have the utensils as you do. Fork in the left – all it has to do is hold down the meat, and knife on the right, because that’s the one doing all the work, sawing back and forth. I’m so right-handed I don’t think I’m even capable of doing it the way you do, with knife in the left and fork on the right. I’d probably end up stabbing my arm somehow.
Apparently this differs between Europe and the US.
In the US, switching hands is common. In Europe, they do not switch hands. (all generally speaking)
In Europe, eating with a fork and knife looks a little different. Though the process starts out the same, with a fork in the left hand and a knife in the right, there’s no switching after cutting. The fork stays in the left hand while you eat.
The controversy? Some table etiquette experts say that fork switching makes no sense, according to The Guardian. Yet for whatever reason, the “cut-and-switch” method has still gained popularity overseas. Still, both methods are considered “correct” in the United States, so pick up whatever of the two techniques feels right. - SOURCE
I do. It feels far more natural to convey food to my mouth with my right (dominant) hand, because the majority of foods that I eat with a fork don’t require cutting with a knife.
As @Whack-a-Mole said, customs differ between the U.S. (where I am) and Europe.
Miss Manners writes for the Washington Post, style guide to the home to 111% of the formal dinners in the U.S. Most ordinary pols have never attended a true formal rules-of-etiquette-guided event in their lives. Some advice about what to do while wearing evening clothes is sure to be appreciated. That said, “Ladies can … secure other timepieces about their persons” is sheer insanity, no matter the time or place, unless they are smuggling bombs into a nuclear facility.
Time and place are the appropriate words. Most of us live our lives with no necessity to adhere to formal rules of etiquette. Ever. There will be expectations that vary with your social circle. Middle schoolers will have elaborate codes of dress, behavior, and phone model. Outsiders can smile, smirk, or roll their eyes but shouldn’t deprecate their importance. Adults continue these codes in subtle and unsubtle ways.
How to behave properly in a restaurant, though, is manners. Be nice to the wait staff and other diners. No more should be expected. What you want to do at a wedding is manners. Don’t be a bridzilla. Don’t be a drunken uncle. Make it a happy time for all. Unless royalty are involved.
Discussions of behavior make no sense unless they consider time and place. They parallel the discussions of language usage here. Rules of grammar exist; rules of usage and style do not. People who claim that only one way is right are wrong.
Miss Manners is smarter than those people. Most of her advice is what used to be called simple common sense. She can tell people how to deflect rudeness without using rudeness back. No column has been filed under the heading Etiquette since 2020. And since her kids are listed as authors, I doubt how much she writes at all.
My point stands. Etiquette is not manners just as usage is not grammar. People conflate them all the time, making an unpalatable smush in our brains. Try not to.