I love the idea!

In my current company we started with HTML and embedded JavaScript at the bottom and Styles at the top. Everything in one file, very easy to find and understand.

It was "a little bit" slower. Pagespeed Insights didn't like it.

Now we are "modern" with CSS and JS in a build process. And nobody knows which file to look at...

My new Projects will start with HTML first, again.

My credibility: 45 years, commercial web programming >25 years, 3 successful web companies founded as CTO