Comment by notKilgoreTrout

I have to disagree, AMP showed that even Google had an internal conflict with the results of WHATWG.. It's naturally quite hard to reach agreements on a subset when many parties will prefer to go backwards to everything but there situations like the first iPhone, ebooks, TV browsing, etc, where normal people buy simpler things and groups that use the simpler subset achieve more in total than those stuck in the complex only format.

(There are even a lot of developers who would inherently drop any feature usage as soon as you can get 10% of users to bring down their stats on caniuse.com to bellow ~90%.)