Last season, Lena Dunham did a fantastic job of engaging critics of Girls by addressing their critique of the show on the show. This season has been a little lighter (so far), so now that she's addressed the more serious criticism, she's moved onto Internet commenters.
What I loved about Marnie's reaction to negative comments on her YouTube video—"I don't read comments"—is that it was a meta-commentary on what the stars of the show (or most celebrities, actually) probably do to stay sane. But the reason why someone like Marnie would even have a "don't read the comments" stance is because she has read the comments. All of them. And it's destroying her.
Why else do you think she's trying to get access to Charlie's account? She could've just called him and asked him to delete it. Or complain to YouTube about a copyright issue. Instead, it seems like she wants to edit the comments to get rid of the mean ones. She cares about what people think. But at the same time, isn't self-aware enough to know that she's lame anyway.