The structure was meant to be more strict syntactically, but almost universally browsers didn’t give a shit because it was way better for users to just “do your best” to process broken or sloppy xhtml/html
That being said, some of the rules meant to enhance the rigidity of html were brought in from the xhtml spec to HTML5.
While browsers will still do a “best attempt” at rendering the page, most websites aren’t even written in raw HTML anymore by devs, it’s either front end single page apps populating the dom or backend generated templates spitting out generated HTML, most of which generally follow the rules of html (except Wordpress, which needs to die in a cave)
Fuck every single person in their AI division. I mean fuck a whole bunch of people in tech sector, but fuck them too