Sure, but the challenge is, if you're in a competitive field and you make it easy for your competitors, you're going to have a harder time establishing job security. Currently many fields like biology, CS, ML, physics have fewer well-paying job positions than contenders, so every competitive advantage makes a difference. I know plenty of professors who got there by carefully writing papers that lacked specific details on how to reproduce a cutting-edge, "hot" paper.

In theory, yes. The actual main point of doing research, from the researcher's point of view, is to advance their career. Typically this means posting cutting-edge results in high impact journals using novel methods. Relinquishing control over crucial details allowing a researcher to continue publishing high-impact papers would increase the competition for the researcher in that academic space, making it harder for that individual to advance their career.

How do the sources of funding (R&D divisions, universities, governments) fit in this picture? Do they have access to the "secret sauce" or do they have to pay extra consultation fees on top of research grants.