It's not about "creative freedom". It's about Google forcing its will on the internet.
- You want to be at the top of our search, in the search carousel? You must implement AMP. We don't care how fast or beautiful your website is. Oh, and only news sites may apply.
- You want to show people the canonical URL? To show the source of the website? No. We will show that it comes from Google, we will actively try to discourage people from finding links to your website, and we will actually launch an initiative in Chrome to kill the URL altogether
- You want to measure activity and engagement on AMP pages? Oh, no we're going to send you a different, very limited and reduced set of analytics data
- You want to show ads in your AMP pages? Oh, it will only be from the ad providers that we, the largest ad provider, allow.
- Do you want to engage in how AMP is defined and designed, and change how it works? No, you can't, we go through a totally opaque process, and we only deliver final decisions that you have no say on. Oh, yes, once we've made all the big decisions (including things like AMP for Email) that actively harm the web, we will create a token "governing organisation" that will do everything in the open, fingers crossed. Not that it matters at all.
And so on and so forth. This is a good article with links to other articles highlighting the many issues with AMP: https://ethanmarcotte.com/wrote/amplified/