I think the argument is that local politicians have too much skin in the game, namely their re-election. Their local laws affect surrounding communities as well

I think the argument is that local politicians have too much skin in the game, namely their re-election. Their local laws affect surrounding communities as well. For example, to get re-elected Governor Bob declares all pollution levels dismissed. Manufacturing in the state booms, thousands of jobs are created and Bob handily wins re-election. Coal ash and chemical run-off is dumped into all the rivers and lakes. Farmers pour on the phosphorus and algal blooms choke the bay killing the fishing for 3 neighboring states. Cancer rates soar not only in Bob's state but also adjoining ones. The coal industry starts contributing to several PACs supporting Bob. But jobs, jobs, jobs. Bob is pretty sure he is going to run for senator after he term limits out of Governor.