It does but I doubt many users end up using it as a habit. The predictions are not available in all apps and the prediction popups aren’t located right where you are both looking and typing like on iOS. So, the user is not nudged to use it as strongly. I forget the feature exists.

This should be the case.

As far as on Windows, autocomplete itself isn’t native, however, the text prediction feature does exist within certain Office apps like Outlook.