I think "commercial success" is a difficult construct. I'm sure dye transfer prints can be made using the information that's available to the general public, if we add up everything published to date by parties in the heyday of the art as well as more recent publications from people like Ctein. Whether one can successfully sell those prints depends on many other factors in addition to how they're made exactly. Finally, given the number of dye transfer printers that have been around and the natural variability in people's temperament, surely, there have been (and maybe still are) printers who have been/were/still are perfectly happy to share everything they know, provided they have the time to answer the questions of the curious souls who set out to pick their brains. Or, simply put - it seems like it's a set of competencies too widely distributed to effectively keep a lid on it, anyway.
Of course, all that removes nothing from the fact that it's a complex skillset that takes both theoretical insight and countless hours of getting your hands dirty (and wet) in order to get anywhere at all. But isn't that the case with many of these processes?