> Who in their right mind would feed an LLM raw HTML in the first place??

I'd even say, is that even a problem ? If your website isn't a front end blob soup and just a relatively clean HTML file, your LLM is totally capable to handle it anyway.

And I'm still wondering myself which incentive do I have to serve my content to LLMs anyway.

There's nothing wrong with "dirty" HTML. Modern layouts require lots of wrapper elements--certainly some sites use them unnecessarily, but it's not reasonable to expect a nice modern layout to use the same number of elements as a basic document. And utility CSS has merits. That's a totally separate concern from inaccessible div soup--you can still use sections, navs, aria- attributes, etc.

If you're working with a marketing team, you'll find that they are desperate to serve their content to LLMs, to counteract the rapidly shrinking number of people actually visiting websites. What I don't want is for that to mean "build the website twice, one for humans and one for LLMs". Websites are for people—bots can adapt.