I've got a top-level comment about why I'd rather not have a feature of the form OP requested. Reddit's block feature originally worked the way the Threadiverse's block feature presently does. It was later changed, and that change introduced problems.
However, that being said, I do think that there may be a real UI issue if people think that they're preventing responses, but aren't actually doing so, and get frustrated. That'd be a legit UI issue.
considers
I don't think I'd use "mute". In IRC, "mute" refers to a moderation action more analogous to what OP wants. I think that that could still produce confusion.
Usenet uses "kill", for "killfile", in the sense of "automatically killing posts from a user". Probably not a great choice either.
Maybe "ignore" would be better than "block", though. I think that that would make it unambiguous what the operation is doing. I'm guessing that the Lemmy devs just chose "block" because Reddit happened to use it, didn't put a whole lot of thought into it.
Related story: I once worked with a guy who had worked on Yahoo Maps, way back when. It was one of the first mapping services to provide navigation instructions. He told me that he was the one who had, at some point, suggested "bear" as a verb for the navigation decisions (e.g. "bear right"). It was a pretty off-the-cuff decision, but apparently it's confusing to some people, since "bear" isn't a terribly-commonly-used term and can potentially be confused with the animal of the same name. IIRC, Yahoo Maps ultimately changed it, years later, but I understand that not only did they use the term for quite some years, but some other services also copied it, so it had considerable inertia.
kagis
https://www.dailydot.com/unclick/kid-gps-instructions-bear-right/
I'm not totally sure about the chronology, but I think that the "old->new" block change on Reddit may have been due to calls from Twitter users. Most of the people I saw back on Reddit complaining about the old behavior prior to the change were saying "on Twitter, blocked users can't respond".
On Reddit, the site is basically split up into a series of forums, subreddits. On the Threadiverse, same idea, but the term is communities. And that's the basic unit of moderation
that is, people set up a set of rules for how what is permitted on a given community, and most restrictions arise from that. There are Reddit sitewide restrictions (and here, instancewide), but those don't usually play a huge rule compared to the community-level things.
So, on Twitter
and I've never made a Twitter account, and don't spend much time using it, but I believe I've got a reasonable handle on how it works
there's no concept of a topic-specific forum. The entire site is user-centric. Comments don't live in forums talking about a topic; they only are associated with the text in them and with the parent comment. So if you're on Twitter, there has to be some level of content moderation unless you want to only have sitewide restrictions. On Twitter, having a user be able to act as "moderator" for responses makes a lot more sense than on Reddit, because Twitter lacks an analog to subreddit moderators.
So Twitter users, who were accustomed to having a "block" feature, naturally found Reddit's "block" feature, which did something different from what they were used to, to be confusing. They click "block", and what it actually does is not what they expect
and worse, at a surface glance, the behavior is the same. They think that they're acting as a moderator, but they're just controlling visibility of comments to themselves. Then they have an unpleasant surprise when they realize that what they've been doing isn't what they think that they've been doing.