Here we go again...
It is in your documents folder, on your own computer, that is in your house. It is also monitored by the cloud, just like your phone; no complaints there. Why are people so stupid that they don't realize this?
Because no one wants their OS constantly scraping every file on their computer computer to find better ways to exploit you under the guise of "oh we are just backing this up to the cloud for you." We paid for software, stop using users as a data source to sell to marketers. I can back up data to my NAS like an adult.