Well. Preloading all pages, including pages that do not take the small-css, & simple native-js limits as well means preloading VERY HEAVY pages.
As it is now — I already disagree with preloading, especially as people with poor connections are people with bandwidth limit who pay by downloaded MB, which are going to suffer financially.
For these people — Preloading everyting is plain rediculous.
So true — the performance boost is not because of AMP, but AMP makes a page tollerable” to preload