Just as medical doctors and lawyers and architects and industrial designers and so on aren't required to freely dispense the knowledge that has been costly for them to acquire, so it is with horticulturists as well. Just because you may be in one of those very profitable professions and regard "messing around with plants" as merely a fun hobby to share about and have competitions about, does not therefor make inappropriate someone else's reticence to give out their horticultural information upon which they are hoping to make a better living.
The adverse effects of losing exclusivity too soon to one's hard-earned techniques can be severe and swift. In economics, the band-wagon effect is very destructive.
As is industrial espionage. I witnessed a nursery, from one year to the next, go from selling about 10 thousands of grafted trees of one species, per year, to one or two hundred--- because a more conveniently located nursery paid an employee to teach them the technique.