Embrace, extend, extinguish.

I would be incredibly weary if someone like Meta, Google, or Microsoft started their own distro. Make a solid distro with lots of bells and whistles few distros have, pre-install it on the hottest gear, poach the best devs away from open-source projects, exert more and more influence over kernel development, wait for a majority to get locked in and then start making parts of the OS proprietary so open-source can't keep up, and the dominoes fall from there.