The issue with this idea, at least as I understand it, is that they're generating higher utilization by sharing and perhaps selling deadhead legs. Any of those things (and anything I can think of that drives utilization meaningfully higher) gives up a lot of the flexibility and precision adaptation to the guy-in-back's ever-changing schedule.

I fly my family in our (piston) airplane for most of our travel east of the Mississippi. Even at piston costs and speeds (both way lower than jets), I can usually beat them door-to-door out to 800 miles and I smoke them door to door for everything under 500 miles. Plus, I'm never waiting for my inbound aircraft, getting the free opt-out feelup by TSA, sweating connections or waiting for my bags.

UberJet can deliver on some of those things, but the closer they drive it to part 121 (air carrier) to make it cheaper, the more they'll give up on the advantage side. I suspect they'll give up a lot of advantages and still not have a cost-competitive product. No one will complain about riding x-country in a Citation X, but they may balk at the $7500/hr operating cost.