What are the ways to protect the site from a negligent user?

Question

CMS

If an inadequate user is wound up on the site, from which blocking and bans do not help (changes ip, registers again), is it possible to somehow find justice for him?
In fact, he only violates the rules of the site, sabotages his work, there are hardly any violations of the laws (although there were insults to other users). Perhaps there are some legal methods? Or something like contacting the user provider with a complaint? (similar to a user contacting a hosting provider with an abuse)

Answer 1

Register with moderator approval

Answer 2

To date, these problems are solved in two ways:
As an option, there is also googleCapcha, but it will only help from the bot. If this is a real person - see above.

Answer 3

There are neural networks that allow moderation on the fly. Block it a couple of times and the system will remember and will not miss this.