@Elizafox we already have a Block activity in ActivityPub for starters, though I think there is more work to be done on filtering.
I am pro-filtering / moderation / anti-abuse tooling, especially in letting individuals have filters that actually fit their needs. I wrote this: https://dustycloud.org/blog/possible-distributed-anti-abuse/
I hope / wonder if that alleviates some of your concerns. This topic matters to me.