I'm not familiar yet with the pre-rendering functionality so I can't comment except to ask - why are you making this contentious feature a requirement of using

I'm not familiar yet with the pre-rendering functionality so I can't comment except to ask - why are you making this contentious feature a requirement of using AMP? Why not allow publishers to opt out of the Google CDN + pre-rendering but still retain all the other benefits of AMP? This type of progressive enhancement would likely benefit more sites/users instead of an all-or-nothing approach.