Whoever has the server has full control. That's how the internet works.

It would be great if that was the way it worked, unfortunately right now it's granular to the instance level, not user level. Not sure it's even possible to get it down to user level unless every user runs their own instance which is unlikely to ever happen. The data has to live somewhere, so we need instances or instance -equivalent to host the data. Maybe if they get it down to where hosting your own instance is super easy one-click ordeal. Then each user would be truly in control.