Do you think that's because of PWA UX being inherently crappy and not, say, the fact that those projects don't have billion (or trillion) USD companies behind them? I think you're mistaking the effect for the cause.
PWAs are a way of lowering the barrier of entry for new devs and that's important if you want to achieve any scale.
> You have a choice
It's kind of a like a thug saying that I have a choice between being slapped in the face, kicked in the butt or subscribing to his Twilight fanfic podcast. Yes, I do have a choice, but neither of the choices is really something I'm looking forward to. Betamax vs. VHS comes to mind too.
I think the line of thinking in the parent comment is a bit naive. There's nothing inherently wrong with PWAs from the UX pov if we take monopolies and FUD into account. That's the reason it is harder to build a PWA with really good UX now (harder but not impossible).
You have a choice, if you don’t like it buy an Android phone. Or a Sailfish phone, or a KDE phone our one of the other open source phones where the only “apps” are low quality PWA crap. Look how successful they are.