People shouldn't have to use an ignore function as a replacement for proper moderating. Like, I'm genuinely curious as to what sort of moderation philosophy looks at someone who has been shitposting for a literal decade and thinks, "Yeah, that's someone we want to keep around our community!" At what point do you call a spade a spade?
Again, it's okay to ban someone just for being a fuckwad. That's part of what a moderator does. If you're not willing to remove someone whose raison d'etre is apparently to make the rest of the community miserable, what message does that send to the rest of us who want to post in relative sanity? Or what sort of message does it send to random passers-by who see people able to post racist or pedophilic garbage without consequence? Because man, that totally sounds like the sort of forum I'd love to join.
(Honestly ignore functions are fairly shitty in principle, since all they do is turn threads where an ignored person is posting into a one-sided unreadable mess. At that point you're better off not reading the thread in the first place.)