Just report posts or users if you think they're making shitposts, but merely making a lot of posts isn't a valid reason unless they're half-assed and unconstructive.
I somewhat suspect that some of the shit posters are using some kind of script/bot to post, although I do not have any evidence (it is just a conspiracy theory). I think people do this in order to get their post count (and rank) up, probably as part of an account farm.
It's unlikely or very rare that people currently on sig deals are using bots or when they do they usually get caught pretty fast. We do occasionally get hit by waves of newbie spam bots that I can only assume are trying to build up their accounts for whatever reason but most of the bots recently are just from scammers, trolls and fudsters like Marinecoin and falling etc.