One of the few actually useful usages of the old block system is actually for vtubers lol.

Vtubers know that people are going to make porn of their avatars, so a large number of vtubers who don't like the idea of seeing porn of their avatars asked the porn artists to block them, because then they wouldn't be able to see said porn artists' posts. Because there's a massive amount of people who post art of vtubers, the vtuber doesn't have the time to actually go looking for every porn artist and blocking them, especially the corporate ones.