Well, HN isn't really of a unified opinion on the matter - you'll find as many people complaining about browser complexity as people who love these features. The thing is, only one choice between having them or not would make it harder to create new browsers.
Blink and v8 are open source. You don't even need to implement the spec yourself. New browsers can piggy back off open source (which is what Chrome, Firefox, Edge, etc also did) to help making a browser easier.
