As you alluded to in your link title. That leaves us back at debating whether a service should be largely available at all, not who should provide it. If the answer is "yes, it should be largely available" then centralization optimizes whatever economies or diseconomies of scale are inherent in that; the reference you and others have made to 49 left hands not knowing what the right one is doing are prime examples of the communication costs and duplicated effort the Wikipedia article blames for diseconomy of scale. It is probably unavoidable in a federal bureaucracy, but maintaing 50 state bureucracies to provide the same public service intentionally exacerbates it. The factors responsible are diseconomies inherent to the scale of those USING, not PROVIDING, the service, but the greater economy of scale in a federal provider reduces those factors below what they would be in 50 state providers. Likewise, the problem of too many chiefs and not enough indians is multiplied fifty-fold when one tribe with one chief is divided into 50 tribes with 50 chiefs. The remaining example from the Wikipedia article is politics but, politics is obviously inherent in any political system so, once again, replacing one federal system with 50 state ones only multiplies rather than reducing the problem.

Federal centralization has flaws, but to far less a degree than those same flaws exist in attempts to meet national needs through myriad state and local governments. When a good or service is a local rather than national concern, it naturally makes sense to address it at that level rather than creating a federal bureaucracy to manage citrus agriculture largely confined to about ten states. When a good or service is a marginal concern at every level it is hard to justify as a community concern justifying tax expenditures at any level. Otherwise, national concerns, however, are naturally and justifiably addressed at the national level, so that economies of scale in supply reduce the diseconomies of scale in demand as much as possible.