Let's say you want a frontend for your server and have never written HTML before.

Where so you start? If you have decided on using Python for the UI you have a handful of libraries each with their own documentation. To get started you need to choose one and then read the guides.

If you decide to use HTML you have a whole lot more resources. I'd argue you'll be able to make a frontend faster using this approach.

I understand the hesitation because of the complexity associated with JS. Maybe you're thinking about bundlers and minifiers when you think about writing a frontend with JS.

But you don't need that. You can create amazing user experiences with a plain HTML, CSS and a JS file.