They might agree in principle, but they’d be pretty pissed off when nothing works when the open their web browser. The golden rule in web standards development

They might agree in principle, but they’d be pretty pissed off when nothing works when the open their web browser. The golden rule in web standards development is “don’t break the web”, ie you can’t just recklessly change web platform features, you have to do it thoughtfully and carefully to avoid breaking existing websites. It’s not a perfect rule, there are exceptions where the breakage is tiny and the benefit is huge, but what you’re proposing is huge destruction and would not make it past the first stage of consideration.