Rondo had much a much greater burden on his shoulders than Sully or KO did. He was our All-Star point guard who had finals experience and a championship ring to show for it. He was supposed to be our leader. With this comes responsibility for our both our struggles and our success. Blame naturally is directed towards him, logical or not.
Think of it this way - if this was a Clippers forum, there would be threads about how the Clippers are better off without Blake Griffin. They've been playing well and beating tough competition without him. But any knowledgeable NBA fan knows that this just isn't true.
Those who said we were better without Rondo conveniently ignore how horrible we looked against the Knicks in the playoffs (you know, when games actually matter) in Pierce's and KG's final year. Go ahead and re-watch that series and tell me that we were a better team without Rondo. That's right, you can't.