"tracking their activity in order to sell it to advertisers. Facebook does that" No, actually as far as I understand Facebook <i>does not</i> do that, and it is a huge misconception. They sell <i>ad services</i> and keep their data in-house. It's the same with Microsoft, just Microsoft has had better security and better privacy policy in general, as they haven't had user data leaks nor have they been seemingly caring about your location and relationships and such.