All they (all big tech companies) have been doing for the past decades has been mining data for ads. Yet, they still are pretty much stuck on the same level:

- I search for and buy something, they keep showing me ads for the thing I don't need anymore.

- I check out some random product, they all think if they just show me one more ad with that product, I will surely buy it.

While I am not immune to ads and they help with brand recognition, it can sometimes serve opposite purpose than intended.

I view it as a change in philosophy that does allow more ads indeed and goes deeper into how microsoft view themselves and by extension their customers:

You have an account that exists on Microsoft - on being somewhere, multiple places at once, even in location and function, in a ocean of Microsoft but whose existence and ownership of existence is finely permissioned.

vs.

You own your device(s).