Good point. Also everyone in this thread, even the OP, failed to realize the main difference/point with the site: it's about LOCAL entrepreneurship and building your LOCAL community, something Brad has been writing about.
http://www.startuprev.com/about
Although, they did do a crap job at emphasizing 'LOCAL' on the site besides using the once in the sidebar description.
SR (gotta refer to it by an acronym you know) is powered by SE. If it could handle HNish load, that would speak volumes about Social Engine, no?
Obviously there's a commercial interest (even if it doesn't drive decisions, it's still there)