I'm not sure it's all that subtle. US governments generally can't use business contracts to compel speech; striking these kinds of rules down was part of tearing down midcentury patronage networks.
Families that benefited from 50s-60s social programs legislated them away in the 80s, leverage mathematical inference to assign themselves exorbitant wealth through arbitrary valuations they decide on, buy up the most valuable assets, and pay as little as possible to us to maintain them.
Horse and Sparrow economics is from a similar era of political thought as spoils systems.
A $200k salary in the 80s had the buying power of $600k now. Past winners were not about to have their legacy deflated, so they changed the rules.