Absorbing those problems is indeed a real concern, and the naysayers have a point: the people that elected the leaders who brought about those problems would likely have more votes than those currently in better run towns.
You are greatly oversimplifying the source of the problems. The economic problems of some cities are results of decades of bad decisions, market changes, unions, etc. To imply that the last mayor of city X is responsible for its problems is a very weak argument. I think that you are trying to manipulate the facts so that regionalism looks like a poor strategy.
