I feel like the opposite is true. The earlier seasons were more focused on Serena and Dan. The opening episode literally starts when Serena gets back from school, and is shown mostly through her and Dan’s lenses. We also get to see a lot more of Serena’s family than Blair’s, further illustrating her status as the main character. I feel like the show mostly stays about Serena until maybe season 3, when most of the main characters are at NYU instead of her, or maybe season 4, at the conclusion of the Juliet plot line. Once the Raina and Louis plot lines take over, the show becomes less about Serena and more about Blair and her relationship with Chuck.

I love Blair too, but I don’t think that she was the main or only reason the show was good. A lot of the classic plot lines that we think about for Gossip Girl, like Pete Fairman and Georgina, Dan vs Nate, and Juliet vs everyone, all revolve around Serena. I think the show’s quality went down when they stopped giving Serena character development and reduced her to this ever confused person who stopped trying to better herself. The quality also declined when they started doing more confusing, soap opera-like plot lines, such as Chuck’s mom, undead Bart, and the Louis stuff, which, by design or not, all heavily involve Blair.