No, it's not because of the iPhone ecosystem that PWAs are bad. It's not because of the iPhone ecosystem that web technologies are ridiculously bloated with no intention of actually fixing the problem. It's not because of the iPhone ecosystem that web apps are inferior to every other type of application you can find.
You can't blame every single problem on "the iPhone ecosystem."
I certainly don't like the iPhone or its software; this doesn't mean that it's somehow responsible for PulseAudio being bad. Not everything can be tied to the iPhone. Really!
I think in fine the PWA problem stems from a lack of education: some developers were exposed only to Javascript and think of it at the alpha and omega of programming. Ironically the web isn't even a platform for developing software to begin with. And because they can't be bothered to even try any other programming toolkit, they want everything else to come in the browser (GPU, SQL, USB, etc), duplicating existing OS functions in a weird half-assed, incomplete, buggy and security-wise questionable way. I don't know what the fix for that is, but probably taking what pure web developers say less seriously would be a good start (in this thread for example, the reference to NPM, a package manager known for the vulnerabilities it enable, is laughable).
You can't blame every single problem on "the iPhone ecosystem."
I certainly don't like the iPhone or its software; this doesn't mean that it's somehow responsible for PulseAudio being bad. Not everything can be tied to the iPhone. Really!