The difference isn't features vs lack of features; it is features vs BENEFITS. This is the thing "business people" bring to the hackerverse.
It's the designers who deserve the credit here, not the business people.
Plus, not all hackers are feature-centric. There are many hackers who understand design.
Speaking just for myself: I don't use SO (or reddit) because of the features they offer. I use them because of the communities involved. I think that's the point here -- there are loads of sites that can compete on features (reddit, meet digg...) but lack something else. It's that "something else" that drives success (partially; I'm not suggesting it's entirely based on some esoteric quality, but that the specific quality can be different for different applications).
Their combined blog readership was huge. They capitalized on that audience, not just the features.
StackOverflow, for example, was sold on features. Look at the early pitches -- it's a reddit+wiki replacement for Experts Exchange. Developers already knew that PHPBB and EE sucked for Q&A. They added voting and editing of old answers, and the demand flowed to them.