They seem to have a high ownership, consensus driven organizational structure. The only time I'm aware the consensus model was violated was when Gabe overruled a veto to ship Steam with half life 2.
It's very interesting to me because it seems to operate similarly to a lot of anarchist shit I've been involved in, but at a highly effective level. And they make oodles of money.
I see it the other way round: they can do all that because they print money.
Not that it's necessarily a bad thing: maybe they stay relevant because they are doing that.