I've been waiting for this comment, I can see how the first set of customization options really seem like they'd help with the personal assistant. It would be interesting to get a full audit of where your data goes and what they can use it for (training your personal assistant, improving their algorithms, responding to Govt data requests, improving ads, etc).
As for incognito, can you sign into windows as guest now? Or even have multiple accounts on the same pc? If so you could create a guest/dummy account if you are interested in giving the personal assistant pure data.
It's still possible to create a local guest account, but that means giving up a lot of settings that I might want to maintain on the regular account, and it's a hassle to have to log out and in again just because I don't want to record something. Maybe I want to plan a surprise trip for someone who also uses the computer or get information about a strange rash that might be nothing without making that part of my permanent record. Maybe I want to let someone else use software which requires an account, like edit a file on Adobe CS or fix a bug inside Visual Studio, without having everything they do become part of my profile.
As for incognito, can you sign into windows as guest now? Or even have multiple accounts on the same pc? If so you could create a guest/dummy account if you are interested in giving the personal assistant pure data.