That's a really good point. When early-stage founders aren't technical, the time/ability they have to "[build] what they should have made" is essentially constrained by whatever change budget is in the contract they have with their outsourcers. And in my experience, a change budget is set based on an (optimistic) estimate of the time needed to add a few unexpected features. It's certainly not enough to allow for major shifts in focus.
Great point - Often times, even after launch, startups haven't reached product market fit, and having a technical co-founder that can iterate the product according to the evolving vision is key. I recommend reading Eric Ries' Lean Startup methodology for methods of finding product / market fit.
