Living in NYC, I have been around a TON of venture backed startups with the classic non technical CEO, technical CTO. Some HUGE percentage of startups see the CTO fired once the tech stack and revenue are stabilized.

The incentive from the CEOs perspective to remove a contender as well as claw back the equity is huge. Early stage the CTO is the most critical, but after real traction they can be replaced far easier than most want to admit.

My advice for technical founders is to always place themselves first, from a legal and organizational perspective. For a technical founder with social skills, a non technical founder brings very little value relative to their vesting in the early stage.