how does that differ from a centralized network. Let me copy/paste your comment

  Yeah but collusion and lack of transparency is what you get with a decentralized network! With no rules to enforce, the powerful can do whatever they want, including acting badly.

into

  Yeah but collusion and lack of transparency is what you get with a CENTRALIZED network! With no rules to enforce, the powerful can do whatever they want, including acting badly.

I see no difference.

You should see a difference, because a centralized network can be governed (by the central entity!). A decentralized network necessarily cannot, because there is no controlling... centralized... mechanism.