Some people are active in the Forum, who's comments I just don't want to see, ever. Because they make me uncomfortable for no particular reason, or I just hate their opinions and don't want to read them.
I'd like it if I could not only block them from privately sending me messages but also hide their Forum actions from me, because I just don't want to see it.
Quotations of their comment by other people would obviously still be visible, I think it would be hard to stop that, but even then I'd still prefer seeing the quotes second-hand.