I think you have this problem of never managing a team and working with internal and external politics. Maybe it could also be you have not much experience working with industry. I don’t know. But it’s incredibly straight forward.
If I am responsible for a product, it doesn’t matter who underneath me is doing the work. Who is the first person that management will look for answers?
Now take that and push the diagram to the top. If my boss manages me and I manage my team, who is going to get blamed if we fail to execute? Me or my boss? Ok now take this a step further and go up to the CEO. If the CEO executes a strat that is not publicly embraced, who is going to get the blame?
You are right. Apple is no ordinary company. But that doesn’t dismiss the CEO from facing the same criticism that every type of leadership at every company at every level gets.
My understanding of the way Apple is run is that there isn't any one person in charge of a particular product at Apple. Rather, Apple’s leadership structure relies on extensive collaboration, where we see small teams consisting of individuals from a number of teams working together on product development within Apple.
This also means that politics and internal rivalry are kept to a minimum, which is by design (I suspect that's why Scott Forstall was let go in 2012, because his not-so-secret desire to one day be CEO of Apple made him very protective of his software team and thus hampered his ability to collaborate with other departments, which made him a liability Apple simply could not afford at the time).
So what this means is that there isn't an airpower team or a Mac Pro team or even an Apple Watch team. Instead, you have a SVP that oversees iOS and MacOS, another SVP of hardware engineering (overseeing iPhone, Mac etc), and a SVP of hardware technologies. This allows for the hardware and software teams to collaborate together as necessary, while avoiding the politicking that comes with a traditional divisional structure (because people are unable to look beyond their own product and see the bigger picture).
This also gives Apple the flexibility to redeploy resources as necessary. For instance, Apple is able to still commit to a yearly refresh of the iPhone and the Apple Watch because they are able to "borrow" manpower from other teams (like the Mac team), but this also means that other products suffer from a lack of resources and manpower. This is possible only because there isn't a "Mac Team" in the traditional sense of the term, so if Apple decides that they want to focus on mobiles and wearables at the expense of the Mac, that's what happens. Which I maintain is a strength, not a weakness, when you consider the bigger picture.
So take the case of airpower. The design team lays out the experience they want their users to have, then the hardware and software teams work together to try and make this happen. And if it fails, who exactly do you blame, when there is no head of airpower? You can't blame the hardware engineering team, because they can't overcome physics. You can't blame the software team because they did their job (as evidenced in iOS 12.2). You could possibly blame the design team for being unrealistic, because that's where the directive originated, but you can't know upfront that the design was flawed, and hindsight is 20/20.
So an idea failed, Apple learned from it, and they will move on. As they always do. My point here is that there really isn't any point in trying to find someone to blame, much less when it comes to a product like Airpower where it was never even released in the first place.
So if you want to grade Tim Cook, do it as a whole. Reflect back on the past year (or years), look at his accomplishments and failings in totality, and make an objective assessment based off that. Rather than zero in on a particular failing here or there while ignoring everything else that Apple has done well.
