My guess is Sam Altman is a better VC than CEO. Better at hype, networking, fund raising, and back room political hijinks than shipping a focused product

He seems to be trying to take almost a "venture studio" approach by throwing shit at the wall, but the problem with these things is always that the "internal startups" are "founded" by people who don't have enough incentive or control over their product to perform as well as an actual startup, and are distracted by internal politics. And frankly, it may also be that the really good founders will just do their own startup vs working on a quasi-startup inside a large org so there's some selection bias as well.