They don't need to be separate. It's just that Apple and Mozilla are not the majority steerers of the development of the Web.
Chrome have stated that they won't do anything to prevent fingerprinting for example.
Re:The Web MiniDisc App (2020)
by tambourine_man on Friday April 09, 2021 @07:42PM
(#26757507)
It’s not malice that I want to avoid, it’s carelessness. Bugs. My browser need not access to my files. Even the camera is a bit of a stretch.
I love the idea of accessing USB devices from JavaScript but I don't want my browser anywhere near them.
Both are great ideas and share technologies, but can (and should) be separate products.