CCC was set up in the 1930's. One of the reasons was to handle the money for entitlement programs: farm programs which established payment rates for doing or not doing things without an appropriation, a cap.
When I worked at ASCS there was still a sharp division between CCC and ASCS. CCC decisions were made by the CCC, composed of the administrators of affected agencies and the secretary's office. There were a couple bureaucrats handling the development of "dockets" for the board, which recorded the rationale for the decision and included the regulations to be published in the Federal Register, Chapter 7, secs. 1400-1499.
There were bureaucratic implications: if Congress passed a program with authority to use CCC facilities, it meant that the Printing and Distribution Branch could tap CCC funds to print forms and handbooks on an emergency basis and, I believe, bypass the Government Printing Office's time-consuming process. And the expenses weren't charged to ASCS administrative appropriation.
On the equipment side, similar logic applied. If equipment could be tied to CCC operations, then it was charged to CCC and not ASCS.
As automation came along, first with programmable calculators and then System/36, etc. the IT types were able to use CCC money.
It was in the early 1990's I think that Congress, specifically House Appropriations, woke up to this loophole. I know SCS people were jealous of ASCS ability to use CCC. Did someone blow the whistle on ASCS? Possibly. More likely the USDA IT office complained about ASCS/FSA bypassing them by using CCC.
Meanwhile the different administrations have found the ability to tap CCC funds for various programs. By now I've lost track of who has done what. The most recent announcement is this, pilot projects for climate change.
“Major policy decisions”? Do we know what that means? There’s a standard of economic impact of $100 million for regulations–but that’s been unchanged since it was first adopted in the 1970s in relation to inflation concerns, not policy.
Arguable the USDA/Trump decision to spend billions from the Commodity Credit Corporation was a major policy decision. But it wasn’t particularly controversial, because it was too esoteric and there were no significant opposing voices to make a fuss. https://www.forbes.com/sites/stuartanderson/2020/01/21/trump-tariff-aid-to-farmers-cost-more-than-us-nuclear-forces/?sh=4fe7a4966c50
I suspect the operational definition is an issue about which there’s a big fight between the parties and/or interest groups. I think the reality is such issues don’t get resolved in legislation, just kicked down the road to the faceless bureaucrats who can be blamed if they screw up and/or offend people.