I don't know if I'm misunderstanding you, but tons of actual things don't belong to the person "holding" or using it. Leased cars, rented houses, work equipment, stolen items. It is a huge simplification saying that "anything belongs to the person holding it, except for borrowed items", which ignores a bunch of history and legal precedent establishing exactly what it is people mean when they say somebody owns something.

Your definition of data ownership certainly is a definition, but it's far from obvious or mainstream. If you texted an intimate photo to an ex, do you consider them as the owner of the photo, meaning that they're allowed to do whatever they want with that photo (as ownership typically implies)?