I have come to the same conclusion: decentralization is the key factor against corruption and lobbyism. That's also why I sympathize with separatist movements in Scotland, Catalunia, Northern Italy, etc.
Decentralization although can have a hard time competing against more efficient centralized entities. A large amount of semi-cooperating smaller entities will not necessarily lead to less corruption, because small town corruption is a very real issue that doesn't get much sunlight.
One example is the internet. Why do large centralized entities seem to 'winner takes all' in many markets in software for example?
Another example is the bay area. Because the area is so balkanized, there is no unified transit system for the entire metro area and caltrain, bart, ac transit and muni all work badly together, with bart not being built as it was supposed to because 1 or 2 counties decided not to play ball.
