Several times now I've had an interaction like:

1. Zach sends a review to me and Ben.
2. I don't want to review the whole diff but I see something that I want to make sure gets fixed, so I reject the diff.
3. Zach updates the diff to fix my complaint.
4. Ben reviews the whole diff and accepts it.
5. I see Ben's acceptance in my email and forget that I rejected it previously.
6. Zach gets mad at me because he can't land his diff.

When Ben accepted the diff, I got an email that says:

benkomalo accepted this revision.
benkomalo added a comment.

LG on my end still

If I was paying better attention, I'd've noticed that it doesn't say "This revision is now accepted and ready to land." but that's an easy clue to miss. Ideally it could add another line that says something like

This revision is still awaiting acceptance from alpert.

or

You're an idiot and rejected this diff before; remember to accept it.

I'm particularly interested in the rejected-previous-diff case but I assume the same logic would apply to blocking reviewers.