Because phones aren’t computers first and foremost. It can be hard to see it at this forum, but phones aren’t computers, they are intended to be general purpose devices to solve a set of problems for the vast majority of people on the planet. And a subset of those problems involve things like money and personal information. So the device needs to be secure, even (perhaps especially) from the end user themself because it needs to try to withstand compromise even when the user is drunk or sad or in a rush.

I am not arguing you need to like where this has led, but you have people in sibling comment threads here arguing we need to push back on things assuming you will use a phone when the whole revolution has been getting most of the world online by making phones widely available.