Why is Atlantis less brittle than Supremacy?

Is Supremacy comparable to the city ship Atlantis?

Only partly; Atlantis belongs to a numerous class of city ships, whereas one unique Supremacy concentrates the First Order's essential functions without redundancy.

A viewer compares Supremacy with the city ship Atlantis. The Atlanteans built dozens or perhaps hundreds of city ships, so their society did not depend on one irreplaceable hull. Enormous scale can be coherent when it is the normal, reproducible unit of a fleet rather than a solitary concentration of state power. The Atlanteans' repeated defeats raise a separate question about how effectively they used their advanced ships. Platform size matters less here than the organizational resilience created by numbers, doctrine, and competent employment.