I think you have it backwards.

If you want to build a client using HTML, then targeting the browser is exactly the right choice.

Javascript-heavy SPAs are much closer to traditional native apps - and lose some of the benefits of running on the web/ in the browser as a result.

There's a lot more reason to consider native app if you are building an SPA than if you are building an MPA/SSR app.

I'm suggesting not using HTML for the client. Anything running in a browser is heavy and slow compared to well written native code.

I think there's an argument for HTML-focused clients - the whole web (including this site) benefits from hypermedia.

I'm less convinced about Javascript SPAs. Perhaps the biggest advantage is that you don’t have to "install" these apps. The browser just downloads the source and runs it automatically in a (somewhat) sand-boxed environment. Also, they work on "most" systems (though mobile vs. desktop is still a thing).