Google scrapes the simplified versions, and when you click the link you're getting it served from Google's servers. Yes, this means decreased distribution costs for the source, theoretically faster load time for the user, but ads - less or more than the original - are 100% in Google's control.

I haven't seen anyone do a side-by-side comparison of a large corpus in a while, but the short version is that you're giving up as much control to Google using AMP as you give up to Facebook publishing on their platform.