Fundamentally it’s just infra reselling as well, with some additional lock-in for that sweet retention.
Back in the day every man and his dog would set up a small scale shared hosting service to put your PHP or cgi-bins on and the interface to it was basically FTP. Nowadays it’s moved on from dragging and dropping scripts to deploying integrated full-stack frameworks with a little ecosystem around it.
I think they look at Vercel and see they're making a good buck with similar offering.