Oh, it's political, all right, and it *is* about pushing systemd and allied turds as wide as possible, but AFAICS you are mistaking the self-interest of duhvelopers for dark corporate plans. I'm no telepath and I would've stayed as far as possible from those minds in any case, but there's a very simple (and ugly) mechanics involved:
* a project joining that group gets an extra leverage when it comes to pushing changes in past objections. Note that devtmpfs (a piece of code that shouldn't have been merged into mainline, optional or not) had been made mandatory by udev changes. In this case the maintainer is the same guy, but the same cross-reinforcement can work between the "vertically integrated" groups.
* any potential fork is going to play losing game against deliberate API changes. Note that there's libudev and I wouldn't bet a dime on such changes not being consciously used as a weapon.
* the more programs grow dependencies on that stuff, the more leverage these guys get.
IMO it's more about bypassing review than anything else. And it's attractive for some people, unfortunately. And then there are fanboys, but how *those* minds operate is something I won't speculate about.