They can, but don't get credit for it in Google's page rank. Which to me makes the whole complaint sound dishonest. They want to have their cake and eat it too.
How do you know that? There are very few people in the world who can claim that with evidence.
- Miami herald rolls their own amp pages: http://amp.miamiherald.com/news/business/article135187364.ht...
- Here's the icon in search for the same page: https://i.imgur.com/43Hk7tV.png
From what I understand, google bots detect the amp standard and flag it with the amp tag for mobile search results.
I'm not sure what point you're trying to make about using js files.