This post is inspired by a couple of instances in the last month or so, but I see this happen at least once a week, so you can safely assume it’s directed widely.
I quite often read comment threads and similar that have in some way got out of hand, whether by going outside a comments/list policy or just annoying the owner of the space. And commonly, the owner or moderator says something like “some of the contributions to this thread have been unhelpful/rude, I’d like everyone to mind their manners/think things through/honour my intent/something.” Sometimes there’s a variant that applies to everyone in a cross-space Internet discussion: “I am finding that many people addressing point X are rude and I wish they’d mind their manners.” It’s usually an attempt to be fair, and not embarrass someone or start a fight.
And me? I wish you wouldn’t do that.
What’s this? Mary’s not in favour of moderation or of setting comment/list policies? Has she seen the free-speech-means-her-blog-too light? Why no, no I haven’t. What I’m objecting to is the vagueness of the call-out. “Some contributions”? “Unhelpful”? Basically this either has a chilling effect on the entire discussion, where everyone thinks that they’re violating the unspecified rules, or is entirely ineffective, because everyone thinks it applies to the annoying people, who by definition are not themselves.
Sometimes shutting down the entire discussion is what you want, in which case, just say so and close the thread. If it’s really specific things that you want to stop, there’s two ways to do this better, in my opinion. One is what I’m doing now, which is a more specific description of unwelcome behaviours. (“No calls for violence here please, no matter whether you mean it, or how common the turn of phrase.” “No profanity.” “No mention of your cats.”) That’s probably best done when it’s a common problem or something you anticipate will be a common problem. The other is calling out specific people with a description of their behaviour. (“Suzy’s swearing is really over the line here.” “Bobby’s constantly talking about his cat in technical threads.”)
Public telling off of a specific person does need to happen sometimes: it can seem disingenuous when Bobby’s the only one talking about his cats and you phrase it as if you aren’t targeting him. It can also make others assume the problem is bigger than it is. Saying it publicly is of course inevitably more of a signal to that person that they’re not welcome, you’re at least risking a fight or them leaving. You could do it privately in some circumstances but if their behaviour is sufficiently annoying or egregious, it has a positive effect on the community to say so publicly, otherwise it looks to everyone else like you’re just fine with it.