Where does this say AMP wasn't motivated by speed? From the link:
> We started working on AMP because we were seeing the mobile web feel clunky and slow, falling behind the tightly-integrated, highly-optimized user experiences that walled garden platforms can offer. Yet we also knew there wasn’t a fundamental technology problem: you could build great experiences on the web with the right knowledge, resources, and management support. Thus we set out to create a framework that would provide a well-lit path to building great web-based experiences: AMP would be well documented, easily deployable, validatable, and opinionated about user-first principles.
Indeed. "Search iframe hack". That's basically all you need to know about their "instant loading" and "caring for speed".
See, they are not really optimised for speed. They are optimised for being pre-loaded from Google's CDN in search results. Or, as OP's article says: "the incentives being placed on AMP content seem to be accomplishing exactly what you would think: they’re incentivizing AMP, not performance"
My point is: AMP was never really motivated by speed. Proof is in all other discussions around AMP, the OP article, the links in the comment I linked to etc. etc.
The only reason AMP is perceived to be fast/instant is because Google lies.
