In this case, it's a 1:1 mapping to what's on the page, so your concern doesn't apply here. Debugging and refactoring is far easier with Python functions than templates, and CSS programmers just use CSS the usual way.

To answer your question, I'll quote from https://about.fasht.ml:

Templates were originally created for web development in the 1990s, back when web design required complex browser-specific HTML. By using templates, designers were able to work in a familiar language, and programmers could “fill in the blanks” with the data they needed. Today this is not needed, since we can create simple semantic HTML, and use CSS to style it.

Templates have a number of disadvantages, for instance:

- They require a separate language to write the templates, which is an additional learning curve

- Template languages are generally less concise and powerful than Python

- Refactoring a template into sub-components is harder than refactoring Python code

- Templates generally require separate files

- Templates generally do not support the Python debugger.

By using Python as the HTML-generation language, we can avoid these disadvantages. More importantly, we can create a rich ecosystem of tools and frameworks available as pip-installable Python modules, which can be used to build web applications.