> The reason HTML doesn’t work well in email is because of bad prioritization, which has led to kludge upon kludge.

Honestly the main reason is that HTML/CSS expanded well over the creation of documents into the creation of apps. Email content does not really need all of that, it will always only support a subset of that causing confusion.

That said, the lack of standards is definitely the worst aspect of all of this and resulted in the current absolute chaos