This would be a great feature - it's one of the best things about Mastodon. You can't filter out all the idiots one-by-one, but then you see someone two people posting some sus anime, or fubar politics, and you can block thousands of idiots with three clicks. It's very satisfying.

Given Lemmy's conversational layout, I wonder if there aren't hidden difficulties. Like if there's a conversation which goes like this:

.
├── person_0
├── idiot_0
│   ├── person_1
│   ├── person_2
│   ├── idiot_1
├── person_3
│   ├── idiot_1

...then which comments should you see? If you block all the idiots, but not replies, then you can't understand the conversation.

I suspect blocking idiots and all replies would work, but I'm not sure.