It means that you've never really developed an actual app. And that you haven't ever thought about all the controls and layouts (with their complex interactions) even in the apps you use daily.

No. Menu isn't "the one control". Menu is one of multitude of controls. Go ahead and try and implement a treeview correctly with nested details (including all the necessary keyboard interactions). Meanwhile treeviews have been a part of native UI kits since... the 80s perhaps?

Oh, and since listviews are so "easy" in HTML, can I finally properly animate adding elements to one or removing elements? With height:auto? And without needing to redraw and re-layout the entire page? Right...

Dialog tag? Does it keep keyboard focus inside the dialog, or do you have to write non-trivial amounts of JS to have this required accessibility feature?

And so on and so forth.

And those are just the most trivial things native UIs solved half a century ago.