The complete abandonment of any form of progressive enhancement is depressing. We need to get some real metrics on user engagement (slow load over poor connections), SEO drawbacks (yes google can index this stuff but does it rank as well?) and accessibility (how well do screen readers really cope?).
Get some facts and start hitting people over the head with them.
Hopefully that will change.
Sounds like your gripe is less with client-side code than with JavaScript as a language.
We have a saying for that in my native language. It roughly translates as "All I hear is mimimi...".
No company will ever publicize this data.
That is not to say that UX should be thrown out of the window for the former, of course.
I do agree that something like NYT shouldn't be a web app.
EDIT: I should mention that a lot of these things come down to requirements, of course. I don't think it's fair to say that every web app must be PWA compliant... it depends!
The biggest argument seems to be laziness: "Progressive enhancement is hard, here's a term that I can apply liberally to give myself an excuse not to bother". That may make a good business argument on a case-by-case basis, but it's not an absolute, and I don't see why it necessarily applies to webapps but not to websites.
Also, React has made progressive enhancement a lot easier than it used to be
> The biggest argument seems to be laziness: "Progressive enhancement is hard, here's a term that I can apply liberally to give myself an excuse not to bother".
It's always going to come down to the requirements and an understanding of who is using your web app.
In some cases, you should absolutely optimize for PWA... Facebook, for example, is a webapp that considers users in developing countries with shotty networks. They also optimize for those with blindness.
Implementing those features in a webapp like Kibana (visualizer for elasticsearch data) would be a wasted effort given the user demographic and the purpose of the app.
TL;DR: "It depends"
EDIT: I just realized I may not have addressed your point " I don't see why it necessarily applies to webapps but not to websites.". I think the answer is simply "Webapps are inherently more complex than websites, therefore, more strict web requirements need to be met". This is an easy way to compartmentalize it, but isn't an absolute.