And to take this one step further. Say you can trust Microsoft 1000%, they are on your team and do everything they can to protect you and your privacy. They are an American company and as such are subject to American laws.
So when elections happen somewhere in the future and some asshole gets elected, they can order Microsoft to use their systems and their data to figure out a lot about people. They can for example figure out who has been using a certain kind of software, who has been consuming a certain kind of content, who has been playing certain kinds of games etc. Then this data can be used to target specific people for punishment for example, a one way all expenses paid trip to a new series of gulag up in Alaska.
You need to be able to protect your privacy 100%, not just for your protection today, but also for the future.