Nostr could definately use an opt in blocklist system where you can subscribe to shared lists where the maintainers of the blocklists then decide who gets blocked for all subscribers of that list. Helps people police the platform in a neutral way, if a block list goes rogue people xan sub to another one.
Discussion
I've thought about this a lot as a Bluesky victim and I believe most of the "big" block lists would just constantly be cultivated by grifters and then "go rogue" (finish the grift)
Better to use a tag-based web-of-trust system where you label things aboutnpubs and their posts. Then people who trust your labels can use them to filter people out of a feed, and it should also become obvious a lot more quickly when a highly trusted npub "goes rogue"