You can approximate the point at which companies decided to own our data by looking at when they transitioned from client-side software with local file storage

You can approximate the point at which companies decided to own our data by looking at when they transitioned from client-side software with local file storage and open protocols to web services with proprietary protocols. Microsoft is still in the process of transitioning. Google, Facebook and Amazon likely never had a data-agnostic phase in the first place.