1. this wouldn't block following people from that relay or browsing their notes or profiles specifically, this would only block it from "global" feeds (like replies feed for such and such).

2. this is one user blocking stuff for himself, not a server admin blocking on behalf of others.

3. in practice reading "global" (i.e. any filter without an "authors" or "ids") would have to be done from a limited set of relays anyway, which means all others are "blocked" by default -- this would be just moving this specific relay out of the whitelist.

In any case I'm not saying this is what the UX should be for Nostr, far from that, this was just an illustrative example idea (I'm taking nostr:npub1acg6thl5psv62405rljzkj8spesceyfz2c32udakc2ak0dmvfeyse9p35c's words here as mine, but I also think he agrees).