I think “highly inadequate” is a big exaggeration. As an example, many people are fairly productive on slack. (Arguably more productive than email.) Native slack is nearly equivalent to web. Another example is google sheets or google docs.
I do agree native had some big benefits. Probably the biggest hindrance to web is that you’re basically downloading the binary from the server and then executing it in line. That leads to a ton of performance optimizations (like optimizing bundle size or async loading things) which make things fairly complicated (webpack) and can also lead to UX compromises. None of which is a problem for native apps.
That's 100% fair, but I don't think that's really the argument of GP. The argument is that the interface is inadequate, not that the result itself is.
With enough force you can definitely fit a square object in a round hole. Not saying I totally agree. IMO it heavily depends. I've seen my share of native monstrosities (seen lots of XAML/WPF apps with zero accessibility and very slow, although WPF is lovely from a dev perspective), and "productivity" covers a lot of ground.
I do agree native had some big benefits. Probably the biggest hindrance to web is that you’re basically downloading the binary from the server and then executing it in line. That leads to a ton of performance optimizations (like optimizing bundle size or async loading things) which make things fairly complicated (webpack) and can also lead to UX compromises. None of which is a problem for native apps.