The internet is so much more than a bunch of peering agreements. You can make a peering agreement with a network that you can't get transit to all you want, but if the underlying physical layer operator says no, you are out of luck. Maybe they'll let you in if you bribe them, maybe not. And this is Geography rules above all else here, which means concentration of access occurs where advantageous locations permit, and central points of control eventually monopolize these. Fiber backbones and undersea cables and major internaps etc. cost a lot to build and maintain. The reason net neutrality is an issue at all is because the tradition of apolitical cooperative peering is under sustained attack from the natural forces of network centralization.

And you didn't address the issues I pointed out about the explicitly centralized 'land title' systems which distribute critical location identities to users. This is to say nothing of the ongoing tendency of higher layer de facto centralization of value location assets such as search and messaging.

Decentralisation isn't non-existent, it is just a temporary transition phase from one centralized hierarchy to another.