The counter to that is what if one agency detects an attack that no other noticed because the culture and practices of that agency diverge from the others in a

The counter to that is what if one agency detects an attack that no other noticed because the culture and practices of that agency diverge from the others in a way that turns out to be positive. There are both benefits and costs to centralization and standardization. We don't want too much taxpayer-funded redundancy, but some redundancy can be a good thing.