> Why wouldn't a company ... let validated customer partners of theirs push batch jobs

A company standing up this infrastructure is presumably not in the business of selling time-shares of infrastructure, they're busy doing AI B2B pet food marketing or whatever. In order to make that sale, someone has to connect their underutilized assets with interested customers, which is outside of their core competency. Who's going to do that?

There's obviously an opportunity here for another company to be a market maker, but that's hard, and is its own speciality.