the idea is that a new thread/topic will need to be approved by the moderator first before it can be displayed on the forum. And I hope it would decrease the amount of spam on this forum.
It would certainly help but would probably be too much work. I actually proposed something similar to counteract bots where every newbie's first post needs to be approved first before it goes live. Most didn't seem to be a fan of it because of the workload it would produce and theymos said it would be too difficult to implement.
Yes, unfortunately nothing is done about them. Even in the gambling section you have topics like, does gambling make you poor. But all those have been moved to the Gambling discussion section. I don't think anything can be done about the Bitcoin discussion.
Many of the low quality threads have been either locked or moved to off topic and there's many more to come. We're probably going to get much harsher with what is allowed there as well but Signature Campaign operators are also going to have to get more strict with how they run their campaigns and if they don't their signatures will be forcibly removed.