These are companies that have allowed so many people to have a website that essentially is a SPA because that's an easy way for them to deploy template based sites. These are much easier to maintain than WordPress sites. Yes, I agree that most of these sites are simply static sites, and I think it would be amazing if these template JS library sites would allow you to render it flat static site once you hit publish or the equivalent. However, they would probably balk at the notion of not protecting their IP with obfuscated code and delivering readable HTML/CSS. I seriously doubt it takes 2MB of JS to operate these sites, and I'm guessing probably 90% of that code isn't used but is just bundled so the same thing is used everywhere.

However, to prove your point, there are many occasions where I've taken as a weekend project to find a template from Wix or similar that I like, and then recreate it in HTML/CSS by hand. It very much is a smaller site. But that's not something anyone here is disputing. The dispute is that you're wanting a fantasy world, and that's not the one we live in.