The ranking algorithm is secret, so one can't know much about how it actually works. But, considering how much effort is spent to increase site speeds, the reality is that that's the impression that developers and site owners have.
Agree with you that that's the impression those people have. I wish Google would be more transparent about the reality. The only thing I've heard actual Google employees say is stuff like "the speed portion of the algorithm will affect only the slowest sites." So if a shitty site like Forbes or CNN is reducing their mobile time from 20 seconds (likely on their bloated regular site) to less than 1 second (AMP) maybe that will give them a boost. But if my site loads in 3 seconds now and goes to less than 1 second on AMP, is it really worth it for me...
