Well I hadn't really worked it out, but I was thinking about how energy was commiditized, then information... and now attention is a commodity too. Tim Wu's book on this is excellent:

I do agree that all networks tend toward centralization over time. Great book on this

Now starting the section now these information empires eventually got dismantled, by the internet, cable, and the government antitrust efforts on the 1950s! Awesome book so far