> Even once every 24 hours will be more than enough.
Depends on the use case. Once every 24 hours is a lot easier to moderate than a minute by minute spam wave.
> IA was just an example, and Tor would be easier.
TOR would indeed be easier... assuming it's not already blocked through other means, as it frequently is. There's a whole ecosystem around blocking TOR and other proxy mechanisms - imperfect and permeable though they may be.
> My point is, you can't get much better than normal shadowbans
Not sure I agree or that you've supported your point - however, even shadowbans are often unnecessary. The goal is never perfect moderation, merely to stack the deck in favor of the moderators for blocking problematic content in terms of time effectiveness until either the moderation effort available can handle it, or until the spammer moves onto easier, more cost effective targets (which even basic shadowbanning can achieve, mooting the need for better tools even if they're available.)
> Also, shadowbanning is a spineless and deeply unethical move.
As a first line of defense against mere rules breakers, I might agree. As a second, third, or nth line of defense against particularly problematic ban evaders and spambots, I will gladly resort to such tools - or worse - and sleep soundly at night.