Also that would probably greatly simplify key management as opposed to having 10 apps all wanting you to use their own mechanism every time you move to another

Also that would probably greatly simplify key management as opposed to having 10 apps all wanting you to use their own mechanism every time you move to another device. Unfortunately so far things are moving in the opposite direction. After Chrome dropped Java support it appears there's no cross-browser way to do reasonably reliable crypto right now.