@LiberalLibrarian I didn't think that a person got any notification that someone had blocked them. Just suddenly they stop hearing you, and no way for you to tell. Unless of course they make a loud dramatic declaration that you're an unworthy person and they're blocking you as you deserve, and then they block you. Which sounds less like the actions of a genuinely offended person of different opinions, and more like the actions of a troll.
@elbutterfield @LiberalLibrarian explains it well. News to me. Makes me wonder if sometimes a block is because someone doesn't understand how to unfollow someone whose interests they realize do not align well with their own.