My understanding is that Reddit would not be Reddit without Alexis. He came up with the name and (I believe) the alien/branding. But more importantly, he fostered a culture of doing the right thing over making an extra dollar, which ultimately enabled Reddit to beat Digg and become a core part of the culture. I wouldn't downplay his contribution to the "birth of Reddit."
This sounds like a loaded question. ;-) But in all seriousness, I think one of Steve's big contributions was rejecting the constant calls for tags, and opting instead to implement subreddits. (I'm just a guy watching from the sidelines; I could be wrong on some of these details.) It's a good reminder that listening to your users is not always the right way to make something they want.
Totally right. In fact, I was fighting with him during our YC summer about implementing tagging (which I also wanted, because we'd be able to spin up new verticals much much faster than trying to build new communities in new subreddits). I'ts a very good thing he won. More on this in Without Their Permission....
