You do realize Microsoft doesn't own the PC platform, right? Nor do they have a store that is close to being as popular as Steam.
Any non-Microsoft game that sells on Xbox, MS gets 30%. On Steam, EGS, etc they get 0%. Any first-party MS game on Xbox gets them 100%, where on Steam, they get 70%.
Microsoft would MUCH rather you play on THEIR closed ecosystem. That does not include PC. They do sell games on other platforms in order to sell software (at a lower revenue) to people who won't be buying an Xbox anyway - PC and Switch gamers.