Yes and no.
I am a big fan of block buttons and use them quite liberally (if someone responds to me in a manner that makes it clear they have no intention of having a conversation? I never see them ever again).
But the problem is that it only blocks it for the user who blocks them. So harassment is still a thing and now even fewer people are likely to flag it for moderation (to the extent that works).
There is obviously room for abuse but I am a firm believer that any block feature must be bidirectional. If user A blocks user B then A and B can no longer see each other or interact. Which would be a fundamental lemmy feature which makes things difficult.
But "just block them" is good for people who are annoying. Not for people who are abusive. And while the latter isn't SUPER common on lemmy, there are still a good number of people who respond to the simplest of things with "Fuck you you fucking moron and you should go kill yourself"