Yes, trolls are an important reason for the mute. Honestly, once they are muted I don't care if they can see me or not. I don't believe I should be able to control what they see. I simply don't want to interact with them.
I make damned sure they are a troll and not sure they are simply disagreeing with me before I reach for the mute. Even then they have to be calling me names, belittling me, and ad hominem attacking for me to say "Okay this person is going to be a time sink and will waste a ton of my time if I keep seeing their posts and being tempted to respond".