Changing your browser is a pretty simple operation if you're not an advanced user who has to replicate his intricate workflow. A large number of people have done it at least once in their lives.
I also don't think we should simply say "it does a good thing". That would mean we are consciously choosing to concentrate on the good aspects while deliberately ignoring the bad ones.
AMP does have good sides, but this is what makes it especially dangerous. Hijacking web sites by fronting them from another unrelated domain is completely completely unacceptable. The good side of AMP lies in making websites lean, but this can be done without the fronting part.