It's because most vendors think of customers as children that must be protected from themselves by removing as much agency and control as possible. This also makes customers completely dependent on them.
@kyle Sounds like a quote directly from Apple's playbook. Only they have learned that if you just use a bunch of pretty sounding words they can sell you it all as a good thing.
@kyle Most adult users really behave like children, and I think most of them really want them vendor to protect them this way
It's also because tight control w/ trust rooted in the vendor is "easy mode" for lazy security engineers. It's much harder to design security measures that treat end users like adults.