In my subjective perception, most of the improvements from AMP came from the fact that all the abusive technology that publishers had amassed on their primary w

In my subjective perception, most of the improvements from AMP came from the fact that all the abusive technology that publishers had amassed on their primary web sites over the past decade or so got temporarily dropped in the forced rewrite. A non-AMP site could be just as fast as an AMP site (minus the initial prefetching) or even faster by not requiring all the AMP-specific stuff, but in practice, the AMP sites were a minimal rewrite of the full site, leaving behind the popups, autoplaying videos, 40 different trackers, ads from 5 different companies, etc. AMP overcame the inertia of just leaving all the crap in and incrementally adding more by forcing the rewrite. Over time, as the publishers had more time to crappify the AMP versions too, they became worse.