@Gargron
Mostly agree, though quoting also allows people to comment & talk with their mutuals while not getting in the OPs face. E.g a friend boosts a comment saying "this is the best movie ever", you might want to respond to the friend saying "oh, that surprises me, I felt x (something your mutual usually hates) was a problem", but saying that to the OP, someone you have no relationship with, would be kind of obnoxious.