As far as I know, only one writer that I used to read somewhat frequently has blocked me. Perhaps he got tired of my comments pointing out things in his articles with which I disagreed. I find it unfortunate, but life goes on.
As for who I block, there are two categories:
1. Scammers who pitch crypto recovery services, "investment experts," and/or invitations to connect on WhatsApp.
2. Folks openly out themselves as antisemites. Note that this doesn't necessarily include anyone who criticizes Israel's government. This because I happen to think that most of the current Israeli government belongs in jail (for corruption) and/or the trashheap of history (for gross incompetence).
If you disagree with what I write and explain why, you may convince me, but even if you don't, I respect your right to have a different opinion (as wrong as I might think it is), so I won't block you.
Bottom line, James, I wholeheartedly agree with your thoughts on Medium commenters.