How a fleet gets trapped in a high-cost spiral

Why did the US Navy move away from a high-low capability mix and expect every hull to perform every mission?

Fewer hulls forced more missions onto each ship, added capability raised cost, and the higher cost then reduced hull numbers further.

The US Navy's difficulty sustaining a high-low mix creates a reinforcing procurement loop. When there are fewer hulls, each ship must cover more missions; extra weapons, computers, power, space, and crew then make each hull larger and more expensive. Higher unit cost reduces the number purchased, restarting the cycle. This mechanism favors a deliberately basic frigate over another ship required to perform every mission.