If they want to do something with your data they just change the terms before they do it, it is so easy and consequence free to legally abuse this that I'm not sure why you think they would do it the illegal way.
Public perception. "Look, we care about your privacy! We won't use your data!"
six months later
Quietly update the ToS to allow them to retroactively use all of your history and data going forward, attempt to fly under the radar and/or gaslight users that it's always been that way
Public perception. "Look, we care about your privacy! We won't use your data!"
six months later
Quietly update the ToS to allow them to retroactively use all of your history and data going forward, attempt to fly under the radar and/or gaslight users that it's always been that way