It is but Google will only put you in the carousel at the top of the search if you use AMP. That's a significant enough driver of traffic where publishers can't afford to lose it.
it's not just the carousel. it's organic rankings too.
we had an emergency AMP project after our traffic dropped 35% due to a smaller competitor implementing AMP and google rewarding them by boosting them in the search results.
That's depressing, but I will remember that when I come across an unnecessarily AMPified URL, I shouldn't blame the publisher for making this possible in the first place.
I'm using software that allows me to load userscripts in Mobile Safari on my iPhone.
I guess you'd call it an "extension"? It feels weird to use that term, as it implies (to me) that there's some sort of extension framework in place. There isn't, it's just code injection.
I though AMP was opt-in for publishers? As in you have to write the front-end spec and pick a CDN to cache with.