My understanding is user activity and user data are distinct, and I'd imagine by now Facebook has enough user data that this might not be as huge a concern as when they were getting started.
No. They announced that people can remove themselves from the custom audiences created by the Facebook pixel. No custom audiences, and the effectiveness of Facebook ads drops dramatically along with Facebook ad revenue. The pixel has become standard operating procedure in most marketing plans and conversion funnels. Many companies lose money on initial traffic acquisition but make it back plus a profit through retargeting. That ability would be gone.
