The problem is most people think their app is super complex and requires some mad thing that's actually complicated when actually its a glorified crud.
The iPhone is 100x more complex and does 10x more than like 10 separate gadgets from the 90s, and yet is also easier to use and more efficient than them all, broadly.
Your CRUD app could be terrible in pure HTML and amazing in Svelte. Or vice versa. But a competent engineer will make a better version with the more modern tech.
Your OS GUI is an abstraction on an abstraction, it's UI kit is on top of that, the browser is on top of that, React on top of that...
People always draw the ideal line exactly at where they learned things / stopped learning things.
And the solution, of course, is a framework on top of a framework on top of JS and the DOM. OK, maybe I'm being too harsh.