Because the people creating the standards (i.e. Google) are more interested in pushing AMP than other solutions. That's the whole issue here.
Google doesn't create standards. They are one of the major stakeholders, but they don't have the final say.
>That's the whole issue here.
No. The issue is that Google built a browser that is better than anything now, and was better than anything out there for the past decade and got themselves into a dominant position. They haven't yet abused that position - contrary to a lot of the posts in this thread - but people are nervous. I can respect that viewpoint because it is something to worry about.
That is leveraging their existing position as a search engine and aggregator to force a standard.