Ever hear of the Pendleton Act of 1883? That is the law that established the permanent and unaccountable bureaucratic state and established the technocracy. (Look it up)
Well it certainly contributed, but what it also brought was a certain stability to government. Unionizing the Federal Government is what totally cemented power within the unelected bureaucracy. The Civil Service Act still allowed the President by executive order to decide which jobs were subjected to the rules and which were not. While it made firing and demoting due to political purposes illegal, it was still rather easy to do so for insubordination.