Maybe, but when said engineer or business takes all the R&D risks, spends the time and buckets of money to measure and refine, it becomes a valuable property and its owner willingly shares it for personal use, sure.
When somebody abuses that permission for monetary gain, it's actual monetary theft. In the West, we call that "piracy". In China, they call you stupid for sharing it with someone that can build it cheaper (of course they can....no R&D cost both to recover and to do new stuff).
I learned early on in my biz career development (we engineers are largely ignorant of business practices -- engineers, usually on the spectrum, are just happy to work on cool shit and give away the farm ..."ooh, shiny plutonium - let's annihilate megacities with just one") that you cannot starve your suppliers. Do so, and the first on their accountants' chopping block is R&D.
's couplers and you're giving him some cashflow to give us private users the next coupler, adapter plate, or gearset.
Buy one from an unauthorized pirate and the money may all go to hookers and blow (English slang for cocaine).
Now you know why I tagged him. Fuck the sabertooths when there's piratin' being done. He made it very clear his drawings were for personal use only. He shared it.
Somebody is making money and is not giving him his cut. He's not the kind of guy to demand it. Damned polite Canadians, eh