Darn.
One of the offshoot boards boards had (has?) this. Nearly every post in it was bitching about posters on the Dope. What’s weird is that pretty much all of them could have been posted to the Pit, but nobody wanted to take responsibility for their posts.
How often does that come up? I can think of a couple of things I wouldn’t talk about on the board, but I wouldn’t talk about them if I was anonymous either.
Infrequently.
A year or so ago, we had a very weird troll who was very aggressively targeting one specific (and mostly non-controversial) poster. The legitimate poster pretty much completely ignored it, but that didn’t stop it from making dozens of sock accounts. I think that it eventually went away because around then, the board started having serious performance issues, and it concluded that it had convinced that poster to turn off the board (one aspect of its insanity was that it apparently thought that the poster it was targeting was the owner of the board).
I’ve moderated on a board that allows multiple IDs, and the differences in both trolling and ease of moderation really weren’t related to the existence of known-to-mods alternative IDs.
I asked the mods for permission to make an anonymous alt shortly after I joined, for reasons like what DSeid mentions, and was told “absolutely not”. So I’m sympathetic with that desire. I will say, though, that in practice, it tends not to work very well. Not because people troll with their alts, but because other posters recognize their “voice” and the alt tends not to stay anonymous.
Shadowbans and their ilk aren’t a good idea in my experience
Spammers must be deleted, so that they go through the shredder and all their data is fed to Akismet, email blocking, ip blocking (which automatically rolls up) etc. There is never any reason to allow a spammer to occupy one iota of space on your forum.
If you’re talking about the place I think you are, you might want to read the Why can’t I see usernames?? HERE’S WHY. thread, in the Discourse About You! (Yes, You!!) forum.
Would it be possible for the mods to set certain threads to allow anonymous posting, to allow people to share details on private and sensitive subjects?
I’m thinking of something like on stackexchange, where you can post without going through signing up for an account, just by entering a name and email address.
We’ve done a few secret threads in which someone (I’ve done it at least twice) volunteers to collect and post anonymous emails for those who want to share something anonymously. Some of those have been really successful (in that there was a lot of discussing and advice given). That sounds like it meets the desire to share personal stuff anonymously for discussion.
Here’s one of those threads:
I took what was (for me) a fairly long hiatus from the board (6+ months) and when I returned the board had installed the new software (I had no idea it was even planned). My original stumbling block as far as accessing my account was my e-mail address that I originally signed up with ; it no longer existed.
To be completely honest, when I first set up this alternate account, my first move was not to immediately notify staff here. No, I briefly flirted with the delusion of maintaining my new identity, changing my posting style and just becoming this mysterious new poster. Well I did say briefly haha. And by that I mean I started all of one info-seeking thread in GQ and very quickly realized I was a damn idiot and went to the SDMB mafia in a hurry. 
So no, im not a Q’anon #Saveourchildren nutcase. Im Ambivalid. (Groans are audible from somewhere deep inside phone)
Hey, welcome back! Do you want your old name back, or are you happy with this one?
I’m getting ambivalid back. I like that name
Fits me much better
Nice to see you.
Oh wow welcome back, I always liked you.
Thanks! Life’s kicked my ass the past year or so, it’s good to be back on familiar territory
I don’t think we interacted, I post rarely, but I noticed you were MIA early last year I think. I even looked up your posting history to see if you did a goodbye thread. Not that I’m a stalker.
Good to see you back, glad you made it through a year of getting your ass kicked.
Dude! Wondered when you’d return to us! Contact @engineer_comp_geek to get your name back so you don’t appear as a sock.
Already did
Glad you’re back!
@Scotty_the_Kid I believe there was even a post asking if anyone knew what had happened to you. Glad to see you back.