I saw this and thought of this thread:
“VBulletin, very popular forum software, has a feature called “Global ignore” that does what you describe. I used to run a large well-moderated professional discussion forum and if we got a jerk in the rolls we would first warn him, then either put him on global ignore or “miserable users”, which is hilarious. It would take people sometimes months to realize they were being muted, sometimes they never did figure it out.
Miserable users was pretty funny, if you decided the person had to go but was big enough of an asshole you wanted to still have some fun, you would turn this on. It would:
1. Slow response (time delay) on every page (20 to 60 seconds default).
2. A chance they will get the “server busy” message (50% by default).
3. A chance that no search facilities will be available (75% by default).
4. A chance they will get redirected to another preset page (25% & homepage by default).
5. A chance they will simply get a blank page (25% by default).
6. Post flood limit increased by a defined factor (10 times by default).
7. If they get past all this okay, then they will be served up their proper page.
After that you just waited for them to get frustrated and leave of their own accord. Passive-Aggressive Nirvana!”
https://ask.slashdot.org/story/17/02/04/1919203/ask-slashdot-how-do-you-deal-with-aggressive-forum-users