I think there's plenty of credit to go around. Stack Overflow's fundamental decisions (gamification, open content, canonicity, searchability) were very significant in releasing valuable knowledge from the arcane vaults of obscure forums and mailing lists, not to mention creating a reliable(-ish) place to go for new questions. The project also represents an interesting template for community curation (which was begun well before launch), that can be learned from by other projects and startups.
Obviously, someone will always build a better mousetrap eventually. They still deserve credit for actually doing it.