Granted I've never done a start up, so maybe I'm just naive. But it seems like if you want to do a technical start up, you should be technically minded.
G'lord, no! How much software is necessary for the minimum viable product of Groupon? Digg? TechCrunch? Facebook? Twitter? FourSquare? StackOverflow? Heck, we KNOW that Digg was outsourced, and that worked out okay. Many (maybe even MOST) startups true problem is marketing/UI/social rather than deep geekery. Many more can get by on half-assed engineering to prove out the initial assumptions and then just rewrite if they see a glimmer of success. Paul Buchheit has said that he rewrote chunks of Gmail quite a few times... It's not unusual.
There are plenty of startups where this would be a disaster but (as web apps get easier and cheaper to build) I think they are increasingly the exception rather than the rule.