The bitcoin example is an especially clear one. You could generalise that even more, and say that the reason why companies exist is because you can make more money by working together with other people than to try to do everything yourself. In other words, the fact that a company is more than the sum of its parts is why this kind of centralisation happens.

My prediction would be that we would see this centralisation overturned at the same point that companies disband as people realise they can do just as well, self-employed. (Which is happening a little bit, actually.)