"The business cofounder essentially gets more leverage the more work the technical cofounder does -- because now there is sunk-cost and a psychological shackle. The technical cofounder just wants to be done with the build-out so the business can proceed and make money -- but the business cofounder has every incentive to expand the MVP more and more since they are putting in no effort (possibly have not quit their job either) and wants more and more before the system can be sold."
Its a very good deal for non technical cofounders! And usually they end up running more of the business than the tech guy. The tech guy is stuck in front of a computer banging out code. The non technical cofounder is out wining and dining customers, doing "partnerships", etc. They become the face of the business. Which does matter, and it takes a psychological toll on you, watching them essentially take your hard work, and use it.