I believe he was referring to the Store on Windows platforms, not Xbox platforms. The Windows Store has games but Microsoft never made a fight against Steam the way Epic has.
They have completely different ToS.
They've rebranded the Xbox Store and Windows Store to both just be the Microsoft Store and content you purchase them (e.g. Movies, Music, TV) is shared between the two. Some Games are "Xbox Play Anywhere" which means you can play them on Windows 10 or Xbox (e.g. Forza Horizon 4) but others are exclusive to either platform (e.g. Flight Simulator). Some games can be purchased for either platform individually (e.g. Halo).
Then you have the weirdness that Microsoft Flight Simulator 2020 is published by Xbox Game Studios but only available on Windows 10.