One-size-fits-all government
The Framers would have seen a one-size-fits-all government for hundreds of millions of diverse citizens as being utterly unworkable and a straight road to tyranny. That is because they recognized that not every community is exactly the same. What works in Brooklyn might not be a good fit for Birmingham. The federal system allows for this diversity. It also enables people who do not like a certain system to move to a different one.