They had it as a minor signal. They could have made it stronger. Posit, for example, that they’d said the carousel was only for sites which rendered in one second on mobile - do you think AMP would really have done more than that?
If your marketing department want one more tracking script and your execs want one more pop up banner etc and each change is bad but not egregiously so, then your average "web guy" at most non-big-tech companies will just do what they're asked to.
With AMP they get to say "it's not possible"
People might have had more room to negotiate on how to hit a performance target but the thing which would have mattered was a number in the webmasters tools console.