The question then of course is: why is the non-AMP version of your blog slower, and could you have improved that with the same effort? Or is it just that people coming there via Google get Googles CDN which is faster?
The easy answer is that AMP forces you to do things like always declaring image height and width. And yes I could do that without AMP, but the moment you're not forced to do something, the path of least resistance is to not bother.
I certainly never would never have bothered setting up a build process to inline CSS previously.
from Google results, yes. That's only one specific (but for many admittedly important) situation, and sounds more like "AMP because that's the hoop Google has you jump through to get preloading", not "AMP because it makes the site faster".
I certainly never would never have bothered setting up a build process to inline CSS previously.