I would rather write 1000 lines of Python than 100 lines of JS.
Nothing wrong with JS, I'm just not fluent in it. Whereas, Python is my native programming language, and I can just see it without looking anything up. This is why I love HTMX. I just want basic web interaction without having to do it all in Javascript.
Yes.
> Which is convenient, but hardly "less code"
It is strictly less code because you're no longer validating on both client and server. It's also more than just "convenient", because it also forces you to stick to the well understood browser UX, ie. all state is URL-addressable.