There is a common trope that developers lack social skills and business understanding and need a "people person" to "handle the business side." This is basically why almost every technical person at big companies is beholden to PMs (who may not even have any technical background) who get paid just as much, if not more, to write word documents, make powerpoints, and tell you what to do. And while it's true that a lot of developers have bad social skills, I'm willing to guess most developers who want to start a company and raise VC money don't fit that stereotype.
So maybe it's non-technical cofounders implementing a vicious cycle of grifting off the technical people, I think it's more likely it's just due to the fact that we have pervasive negative stereotypes surrounding technical people's ability to do non-technical things.
It’s not that technical founders don’t have people skills: they don’t have the time. Going full bore into product development only to be interrupted by a potential customer asking about pricing plans is a big time suck, but it’s vital if you are actually building a real business.
Wild speculation: It is the founders that have developed a deep understanding of both computers and people that are likely to be successful. These two domains are very deep and take a long time to learn well (say twenty years at a minimum). Studies suggest that generally people focus on one or the other (men generally focus on understanding things and women focus on understanding people). Find those people who did both at a young age and give them some resources to run a business and they might do very well. As Paul Graham said somewhere, these types of people are only likely to want to start a business as mundane as "make file backups really easy and reliable" if they will be very successful and that success will let them hang out and work with similar people.
So maybe it's non-technical cofounders implementing a vicious cycle of grifting off the technical people, I think it's more likely it's just due to the fact that we have pervasive negative stereotypes surrounding technical people's ability to do non-technical things.