This is far from true. Example: Given the amount of resources Microsoft has and all the effort they put in UX it seems reasonable they have made the best UX decisions
No, that's provably not true.
It seems logical that the large resources of big companies would work that way but that's not how the real world works. It always comes down to just a few people and their taste. Rarely are these kinds of decisions made based on anything more than a few people's opinions whether it's Microsoft, Google, Apple or Facebook. Whoever is the lead programmer for a particular project or lead UX designer for another or one of the 2 or 3 people around them decide this stuff based on nothing more than their professional opinion. That opinion might be more informed than your average joe but it has nothing to do with the size of the company and their "considerable resources".