Yes; I think that's the real impasse here. As I say, I think there is a middle ground where the device owners keep the keys, but programmers can run whatever software they want within sandboxes - including linux. And sandboxes aren't just "an app". They could also nest, and contain 3rd party app stores and whatever wild stuff people want to make.

But a design like this might please nobody. Apple doesn't want 3rd party app stores. Or really hackers to do anything they don't approve of. And hackers want actual root.