I say that after 3 pages, see if there is any actual conversation going on and if not, lock it.
Absolutely. Most of the posts there doesn't have any actual discussion going on and is mostly just a heaven for the shitposters. I've stopped going there already. IIRC, some of those threads were either locked or moved to offtopic.
Another handy change would be to block bumping old threads (ones that haven't had a reply for six months). If there is a news update on the topic. then a new thread with a link to the old one would be more productive.
If the thread is very old, you can try reporting it as a necrobump. They would most likely be removed.