My theory
It coalesced at a time when science was becoming more accessible to the masses, more educated technicians running around engaging in work and trade.
And these technicians were frustrated by bosses who didn't understand the science and technique behind things.
So there was great inefficiency because the bosses hadn't caught up to the technicians in their understanding of the world.
And so the political idea of "put in charge the people who actually understand the problem" caught hold of the technicians, and they were fired up for a period of time and they called it technocracy.
It's also the height of real problems being solved relatively simply with technological advances.
Then realized they too didn't understand the complex nature of the world
Sounds like early AI..
Not just that but the 30s was the tail end of a period of reduction and unification in science. If physics and biology (large portions of it) could be reduced to a handful of principles, why not economics and politics. Darwin, Maxwell, Einstein, Hilbert, the Vienna Circle. It must have seemed like science was on track to explain more or less everything.