Yeah, but the Mesh Network is still free, secure and decentralized. The cables are not part of the Mesh Network. Although sharing a common access point to the world wide web the Mesh Network itself is still free, secure and decentralized.
Without access to the rest of the internet a meshnet is reduced to a local area network. Which still has its use cases but is not viable for any global applications such as a cryptocurrency.
Mesh is the obvious path of development to a private, secure decentralized internet development.
In terms of centralization the network infrastructure should be the least of your worries. It's Facebook, Apple, Alphabet etc. and their walled gardens and consolidation of data / content / power that you should worry about. That's where the centralization of the internet, the loss of privacy and autonomy take place -- on the application level, not the network level.
Don't get me wrong, meshnets are great and I love seeing the many meshnet initiatives around the world. But they too have their limitations and are only a piece of the puzzle.