The problem is that you can and should build fast, lightweight websites without AMP, but that won't improve your Google search rank, which will favor and only reward the AMP version, thereby forcing a specific, self-serving set of means instead of rewarding the ends, which are achievable in countless other ways. This results in the ridiculous, absurd and unnecessary situation where heavy websites that build a lightweight, Google-hosted AMP version on top are better off than your hopefully well optimized, yet AMP-less website which has been lightweight from the beginning.

Fast, lightweight websites are great - it's just that AMP is completely unnecessary to achieve that goal and instead serves as a way pretense to keep users and content within the Google eco system. Google could just as well rank sites on how fast and optimized they are, regardless of AMP usage, and I'm sure we would see a race to remove the bloat the web is currently plagued by.