CG: And I can’t count the number of laments from those gurus that I’ve seen while Google-researching about this topic, crying about the general population ignoring the standards of etiquette … apparently, the majority [of etiquette gurus] has decided that they’re irrelevant old fuddy-duddies, and they bemoan their obsolescence.
However, I don’t think that some complaints you haphazardly found on the internet negate the significance of best-selling etiquette books and syndicated columns, when we’re considering whether etiquette conventions are really “irrelevant” or “obsolete” in the society at large.
Hypothetically, if I wanted to change them [etiquette conventions], what would I do?*
Exactly what we’re doing here, non-hypothetically: namely, talking with lots of other people about the most tactful ways to convey a “no-kids-invited” message, collecting experiences about what ways seem to work best, and spreading advice about those ways around to people who are looking for it.
And then eventually, if a good strategy catches on and becomes popular (and is sufficiently tactful), people who write books about etiquette will incorporate it into their standard canon of conventions. That’s how etiquette always works.
Religion is a social construct with codes of behavior and interaction. Now substitute ‘etiquette’ for ‘religion’ in the preceding sentence.
It doesn’t make your analogy appropriate, because as I said, your personal religious beliefs and practices are nobody else’s business. Your social interactions with other people, on the other hand, are other people’s business.
*So if I put out a book claiming that it is customary to extend one’s middle finger at the happy couple after a wedding, that makes it so? *
Of course not. The reason etiquette advice is commercially successful is because it’s widely perceived as useful, meaning that it generally squares with people’s ideas of polite behavior. It would be completely silly to think that just by publishing a book prescribing whatever weird behavior rules you feel like making up, you could create a wide consensus that they were appropriate polite behavior.
You seem to have this weird idea that etiquette is something that snotty etiquette authors arbitrarily impose on an unwilling public, instead of realizing that etiquette is actually codified by such authors, over time, from the behavior of the public. Not all of it, of course, but the standards of manners that are widely approved and practiced by the public.
When I have a piece of information… that I consider important for others to know… I tell them that piece of information.
But how you tell them is affected by the rules of etiquette, right? If you notice from across the room at a party that your grandfather accidentally has his fly open, and you consider it important for him to know that because he’d want to zip up and not go around with his fly open any more, do you take the fastest and most efficient means by yelling across the crowded room “Hey Grampa! Zip up your pants!”
Or do you refrain from that on the grounds that it would be rude, and instead let him know in a more subtle and private way?
How you convey something is very often as important as what you’re conveying, which is why we have etiquette rules about generally-accepted ways to do so.
*I do not rely on a manual of elitist snobbery nor multiple manuals of elitist snobbery. Thus, I do not feel compelled to snub those who have not read it or who choose to disregard it. If someone conducts themselves in an offensive manner … I tell them that I find that conduct offensive.
It gives them a chance to either adjust their behavior with no real harm done, or to choose not to adjust their behavior. And if they choose not to adjust their behavior, then I can rightfully snub them. Because I’ve clearly delineated the nature of the offense and given them an opportunity to correct it.*
You poor dear. 
Honestly, I’ve gone beyond feeling irritated at you and now just feel sorry for you. In a quixotic attempt to liberate yourself from what you perceive as “elitist snobbery”, you’ve designed yourself a nightmare of conflicting individual standards of behavior, full of people making up their own personal definitions of what counts as offensive and trying to get other people to conform to those definitions by accusing them of having offended them, and then having to snub them when they won’t conform. What a sad mess.
And all this just to avoid having to take any advice about etiquette conventions from the dread “manual of elitist snobbery”. It really is so much simpler to put a little effort into finding out what the basic common standards of manners are and then abide by them, with a bit of creative adjustment when necessary, than to condemn yourself to renegotiating mutually acceptable standards of manners with every new person you meet.
