You can still reply to someone that mutes/block you on nostr, so I wouldn't call it cancelled.
yea but noone is going to see it. Worth nothing.
Uh, everyone that did not mute you will see it, and especially those that are following you will see it on their feed (at least on Amethyst).
To me, to "cancel" someone is to force him away from interacting with your community at large, not just yourself. You can't do that on nostr, you can just choose to not see what he writes. Even if clients did not have a mute button, you could still just past-scroll and ignore, so it literally just like real life to me.