I guess many web developers would climb on a roof and throw stones, because then they really needed to learn HTML and using its elements semantically. And probably many of their web components would no longer type check either, forcing them to reimplement or use simpler elements.

There was a time where front-end devs would have sat down and cried had they had to make closing tags.

Ever heard of XHTML?

There's a reason it's dead.

This is a great idea!