It is kind of wild to me that anyone would think that blocking someone = making it so they can't see you. To my knowledge, that is never how it worked. It's not how it worked on old school forums and boards, it's not how it worked on reddit, it's not how it ever worked on hexbear or lemmy in general. Maybe it's how it worked on twitter and that's why there are apparently some people who are confused about it, but I don't know, I never used twitter or clones like bluesky.
No, when person A blocks person B, all that results in is that person A will no longer see anything that person B posts. Person B is essentially unaffected. When you block someone, you are applying a filter to what you see, not to what they see. So you are correct about how it works, but I would not call this an oversight in lemmy, it's simply always what it has meant to block someone. And it makes sense to me that it works this way because one user should not be able to dictate what another user is allowed to see of what is publicly posted, but a user should absolutely be able to choose what they themselves want to see - which is consistent with how blocking someone does work and should work.

banning the antinatalist sub (exceedingly rare reddit W).
Don't buy your treats, ~~steal~~ expropriate them. Problem solved.