In practical business terms I would strongly suggest website owners build ultra-light versions of their sites. If you have international aspirations your site should work on Opera Mini. If you have a big audience it is very reasonable and worth it to have desktop/tablet, smartphone, and ultra-lite versions of your site.
Reposting part of a comment I made a month back on AMP:
#1 There is a big problem with mobile sites. I'm using a recent iPhone and many popular news sites, without ad blockers, are as close to unusable as the worst websites I've ever been to, dating back to using Internet Explorer in 1999. Auto playing inline video ads that slide in to view, just insane. These things clearly kill time on site and reader retention. I have theories about why publishers are ignoring this, but who knows.
#2 Google is using AMP to co-opt publisher's traffic. This means users are scrolling to another story from another publisher or easily bouncing back to the Google results when they land on your content. (See the X in the story link on the animated gif example.) There goes your time on site and long term user retention. If #1 was a problem for you already, you probably don't notice.
#3 AMP & Instant articles are going to put a stranglehold on third party ad networks and represent a very real anti-trust issue. There are a bunch of other privacy implications too, which have been discussed in length. Publishers should be thinking really hard about their future.