The “loose” standards of HTML led to some really awful things happening in the early web. I remember seeing, e.g.,
<large><li></large> item text
to get a bigger bullet on a list item which worked fine in Netscape but broke other browsers (and since I was on OS/2 at the time, it was an issue for me).
Really, in 2025 people should just write XHTML and better yet, shouldn’t be generating HTML by hand at all except for borderline cases not handled by their tools.
Unfortunately XHTML5 doesn't exist and if you try to force the issue, you have to re-declare all of the non-numeric HTML entities in your own DTD (I abandoned the idea here). I'd love to use XHTML, its just not viable anymore.
As for generating all HTML, that's simply not possible given the current state (of open-source at least) WYSIWYG HTML editors.
I stopped using entities once we had UTF-8. I suppose there’s a case for the occasional < > but beyond that, I have no problem typing “‘—’” or üçě when I need to.
Really, in 2025 people should just write XHTML and better yet, shouldn’t be generating HTML by hand at all except for borderline cases not handled by their tools.