Sure. Or you could use Bazzite. But I want something I don't have to faff around with, like the Steam Deck. Plug it in and start gaming. That's the selling point. If Valve can achieve that, make it perform well and be affordable, they have yet another goldmine.
There is no master plan. They've started this project and scraped it multiple times. They've fired the entire team multiple times, even sold the team the tech once.