I think the failures of iPadOS are really illuminating about the contrasting strengths of closed top-down design vs open stochastic exploration. Apple loves to craft an experience, and this design approach is great at taking large steps to get out of local maxima, and find new rich areas. Because they control the entire process they are theoretically able to make bigger moves and take larger design risk. For example, they could have never made the iPhone without this method of development. However any singular design vision is ALWAYS going to have blindspots that prevent it from reaching a better local optimal state. When it comes to figuring out these blindspots and moving towards a better local maxima, the best approach is having a lot of individuals experimenting widely.
For example, if outside developers had more capability to explore different ways of managing files on an iPad, it's likely that someone would stumble upon a really great way of handling it that gains traction, and that Apple could adopt more widely.
I think there's some connection between your comment:
For example, if outside developers had more capability to explore different ways...
...and these 2 sentences from the article:
For the sake of this argument, let’s posit that there exist tens of millions — perhaps 100 million — users who love the iPad for what it is. People who feel empowered, not hamstrung, by how it works, and who have no or very little need for a computer that exposes the complexity of a desktop OS like MacOS or Windows. And that there exist tens of millions more people who enjoy having an iPad to complement, not replace, their desktop computer.
If someone did come up with an iPad competitor that had all of the ease of use, UX simplicity, and ecosystem benefits, but also better enabled power users with something nearer a desktop replacement, then this would simply kill the iPad.
The fact that Apple seems reticent to do this themselves, indicates that there is a kind of organizational blind spot there, driven by self interest. Either that, or there are typical Apple long term plans that we're not fully aware of, and they're taking their own sweet time.
For example, if outside developers had more capability to explore different ways of managing files on an iPad, it's likely that someone would stumble upon a really great way of handling it that gains traction, and that Apple could adopt more widely.