It's more of a mutually-consented handholding with small amounts of arm-twisting. Your content needs to make money for you to stay afloat -- if it doesn't, you're not in the target market for AMP -- so Google gives you some tools to that they can surface your content, and you get their ad and analytics infrastructure and their preferential treatment; the premise is both Google and the publisher win more than they lose.
But this is clearly only a plus for Google, by abusing the relationship with the publisher. The logic is circular here. If Google wants people to make better sites, then why don't they just rank sites higher if they aren't full of bloat?
If I read the above posts correctly, it sounds like it's not just Google that benefits; supposedly Google provides ads and such, which provides the publisher with revenue -- the publisher would otherwise have to find ad networks and such themselves. If a publisher already has advertising revenue sorted out, and they're OK with the expense in terms of time spent managing that, then there's little incentive and so they pass.
How much of that is correct? I don't know. I'm just explaining what (I think) the posts above were trying to say.
