First: I run a popular newsletter that uses custom HTML theming and CMS customization. I don’t work in marketing. I just genuinely think HTML in email is actually a value add. Not everyone you disagree with works in marketing.

Secondly: The problem you’re pointing at is bad implementation of standards, which is entirely on Microsoft and Google. (Mostly Microsoft.) The reason HTML doesn’t work well in email is because of bad prioritization, which has led to kludge upon kludge.