This seems like the same unprovable nebulous “don’t try to fix or deter bad things because people will thwart you in the end, secretly.” So far, I’ve only seen limited ugliness on lemmy, then the user is banned and it seems to get better

Super late reply, but I think this is a fantastic point. It’s such a strange argument, too, and I’ve seen people experiment with this argument on, say, hackernews.

There’s a long list of arguments against moderating that experiments with different ideas from every possible angle. One argument is “banning won’t work, so don’t bother!” Another contradictory one is “banning is bad because it’s so powerful and effective, it effectively infringes on free speech!”

Another variant is a kind of whitewashing, where someone always just so happens to argue in favor of keeping trolls around, but for reasonable-sounding reasons that split the difference on every point and generally just don’t treat harassment as a big deal.

The only consistently I’ve ever found in these arguments is that they seem to work backward from a preferred outcome: supporting, empowering, protecting trolls. I like to think I’ve read enough comparative politics and philosophy that I could look at a meandering “don’t ban the trolls” comment and squint through it and see what a person’s underlying values are. But more often than not the only thing that clearly emerges is that it just so happens to be an argument for keeping trolls around. And it’s part of the broader experiment with seeing how far they can go in pushing the limits with bad faith arguments.

don’t try to fix or deter bad things because people will thwart you in the end, secretly

That is a misunderstanding. I didn’t intend that part for any kind of moderation situation. I mean this in the context of a user intentionally trying to trigger certain moderation techniques.