We just had a thread the other day about how AMP is an anachronistic, proprietary platform that breaks functionality that is otherwise completely fine for nearly all devices.
I have no particular stake in the specifics of AMP here, but X being a subset of Y does _not_ mean that X is necessarily no more complex than Y. Adding restrictions on something necessarily gives a subset of the original thing, but abiding by those restrictions may be complex.
The example that comes to mind is that every formal language on {a, b} is a subset of the regular language given by /[ab]⁎/. It's incredibly easy to recognize the latter language, but there are literally undecidable languages that are a subset of it.
In that case it is no more complex. AMP is more structured than HTML, has fewer valid tags and attributes, and has an official implementation documentation that expresses how to design the perfect AMP UI in a much more concise and simple way than the HTML docs.
