I've always understood why they do this. Its data collection, its a really weak lock-in to their ecosystem, it gets users embedded into Windows more. Its just not very compelling, just another hoop to jump through. Also I don't really see Microsoft accounts as a major SSO offering on many sites, its usually Google/Apple/Facebook and maybe some other related sites. Seems logical to call this one done and just focus on making a more enjoyable experience in Windows.