But for anything non-trivial, that app that does everything person A needs doesn't do what person B needs, and vice versa. It mostly does what person C needs, who is a whiteboard made subset of the most used features and doesn't match anyone.

It's not just UNIX-like flexibility, it's human uniqueness, and the uniqueness of the tasks they perform and the ideas they have. It's also the difference between owning and knowing how to use a tool, versus renting someone to do it for you who might help you today, but could rob or hurt you tomorrow.

Just consider how we spend decades to teach new humans to read and write as well as they can learn it, versus just giving them a bunch of emoticons to signal when they're hungry or sleepy or bored. Because we expect them to become full peers, and architects of their world, responsible for the next generation, not just consumers picking options others prepared for them. And we don't care if they want that, because we know what they don't know, yet. We base our judgement on the information we have, not the information they lack.

Making an exception for computer literacy just because it is hard (as if language and reading and writing aren't until you get used to them) set us on a terrible path.