Please fact check me on this, but the ostensible initial justification for AMP wasn't decentralization, but speed. Businesses had started bloating up their websites with garbage trackers and other pointless marketing code that slowed down performance to unbrowsable levels. Some websites would cause your browser to come close to freezing because of bloat.
So Google tried to formalize a small subset of technologies for publishers to use to allow for lightning fast reading, in other words, saving them from themselves. AMP might be best viewed as a technical attempt to solve a cultural problem: you could already achieve fast websites by being disciplined in the site you build, Google was just able to use its clout to force publishers to do it.
As for what it’s morphed into, I’m not really a fan because google is trying to capitalize on it and publishers are trying various tricks to introduce bloat back into AMP anyway. The right answer might be just for Google to drop it and rank page speed for normal websites far higher than it already does.
