> because for most people a phone is not a toy (or at least, not just a toy) - it has their communications history, their bank information, their passwords, any many more. And it's really easy to steal people's phones on the subway. This isn't about freedom of computing, this is about the fact that an iPhone in BFU is nearly as secure as a GrapheneOS phone.
If that were the entire reason, the straight-forward thing would be to give the user tools to secure the phone, such as setting a password and encrypting data based on that password.
It wouldn't make sense to spent enormous amounts of resources to "secure" the phone against its own user, yet that is what they do.
I think a more honest explanation is that they aren't just securing their own corporate power, but also the power and business models of all kinds of app developers - this way, developers can sell trivial UI improvements as "premium features" or even put in deliberate anti-features and the user can't do anything about it.
Games can put in loot boxes and microtransactions, YouTube can declare that keeping a song playing and putting the phone away is a premium feature and movie rightsholders can decide the exact circumstances under which a movie may be watched.
That's all before the ubiquitous tracking and data collection.
Everyone wins, except the user...
> and just wants to be able to open LOVE-LETTER-FOR-YOU.TXT.vbs without having their 401k get drained.
So do I, even if I'm a tinkerer. That's what sane permission settings and - if you like - a locked bootloader are for. What you don't need for that is to restrict the owner from unlocking the bootloader.