I don't really have much big-picture analysis in the wake of Andrew Sullivan's departure from blogging. My reaction is strictly personal. I've spent the majority of my career as a print journalist. In 2008, when I first started blogging, I had two models in mind—Matthew Yglesias and Andrew Sullivan, and I only knew about Matt because of Andrew. I started reading Andrew during the run-up to the Iraq War and thus bore witness to one of the most amazing real-time about-faces in recent memory. But it was a sincere about-face and it taught me something about writing, and particularly writing on the Internet, which guides me even today—namely, that error is an essential part of any real intellectual pursuit.
Back when I started blogging, there was an annoying premium on "public smartness" and "being right" among pundits, journalists, and writers. Likely, there is still one today. The need to be publicly smart and constantly right originates both in the writer's ego and in the expectation of incurious readers. The writer gets the psychic reward of praise—"Such and such is really smart" or "Such and such was 'right' on Libya." And the incurious reader gets to believe that there is some order in the world, that there is a stable of learned (mostly) men who will decipher the words of God for them. The incurious readers is not so much looking for writers, as prophets.