Thanks for the replies. Looks like the best option is to set up an ignore list manually, that's a lot of work though, not the ideal solution.
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The ignore button works very well for me and I don't see it as a hard work to do. You just use that button when you see an user shitposting.
Of course, if you're going to specifically look for those shitposting through threads and ignore all of them, it's gonna take a loong time and will probably be boring as hell.
But if you take them out one by one randomly when you're posting in a thread, they'll all be ignored in no time and you won't even notice the effort you're doing.