I can put together a full HTML/CSS/JS UI for a screen in hours where it will take me days to do it on Android or iOS alone, ignoring the fact that I'd have to make sure it's responsive on all those platforms anyway (because tablets), then still build it for windows, linux, mac, and sometimes a web version anyway.
Hours for a single screen ? Exactly what I'm talking about. The fact you think that's quick is worrying.
I'm talking from start-to-finish creating the UI, wiring into business-logic, handling UI state, making it fully responsive, etc...
I've used WPF, QT, some old java swing stuff, and the Android studio layout editor, and none of them are a fraction as fast and capable as a well setup react web application (which to be fair, took a good chunk of time to setup).
And you'll need to have a designer look them over or design them in the first place for each platform, and write documentation for each platform, and test each platform, etc...
In many cases I won't argue that a native app won't be better for the user in many ways, but you can't argue that it's faster to re-create, document, and test your UI 5 different times.
No, it won't. Building any non-trivial UI in HTML takes orders of magnitude more effort and time than building it in a UI toolkit that was actually designed to build user interfaces in.