Someone please correct me if I'm way off the mark here: I assume the reason behind this purchase is to keep Windows relevant as a gaming platform. It looks as though Windows is becoming less relevant overall as a computing platform, and alternative platforms such as Steam Deck are beginning to pose a major threat to one of their major market demographics: Gaming.
Windows has been a decent development platform for Linux via Proton. ;)
Maybe they are just worried about the long game of Proton eventually eroding MS's share? But this looks more like propping up Xbox and Gamepass than Windows losing share (at least short term).
I'm confused how you came to that conclusion. Steam isn't threatening Windows gaming because a linux installed device sold 2m units. An Windows is still very relevant for computing despite more enterprise trying to move off Windows to avoid licensing cost.
I think the reason is much simpler and smaller scale: Microsoft has always been behind in the gaming space and a huge 3rd party company with valuable IPs can bolster some incentive to buy Xbox and even PC's. It also further gives value to gamepass which seems to be their big focus this generation.
