If you’re using backend templates it’s already coupled. The css as well. It’s a myth that separate langs in separate files == decoupled. I didn’t realize myself until recently—just got so used to it.

The main way around that is the SPA/API architecture, but that comes with huge complexity drawbacks as well.

Nothing special about html, at least as a Python string builder you can factor it and use tools. It can also be put into separate files. So many upsides and little to no downside besides initial surprise.