It was never allowed and has been actively pursued and enforced by the FAA and various other Agencies for years. If you were flying an upgraded 206, there is a very good possibility it may be a converted 206A as many of these incorporated the factory improvements that came with the evolution of the model. You could have easily checked your aircraft logbook to see if it had been modified in accordance with an STC or by referencing the 337's for any modifications that have been accomplished, and then you would have known the complete status of your helicopter.
How would you know that your airframe hasn't been crashed and incorrectly rebuilt or repaired? How would you know anything about its history or configuration if you didn't have the applicable records for the aircraft, but had records for another aircraft which was totally unrelated? Why bother keeping records at all? In fact, why license pilots or technicians, why train, certificate and maintain currency. Why not disband the FAA and just have a free for all. You could put any old engine in, perform any structural repair that you thought might be good enough, buy your parts from anywhere, use old parts from crashed machines, corroded old junk, timed out blades, just whatever you felt like and fake the paperwork as required. Rather than follow the carefully established global regulatory network built on years of experience (often bad) why not just throw it all away and join the protests at CHAZ in Seattle in support of aviation anarchy? In fact, if you went to Seattle you could share your opinions with the unemployed former Boeing employees from the 737 MAX program, who potentially shared a similar philosophy to yours.
Your user name might take you directly to an individual that did all of the above, got caught and skipped town. In the meantime, you should offer your services as an expert witness to one of these crooks that got busted - I'm sure the Judge will pay close attention to your opinion!
I personally think it's great when these guys get caught, and they deserve everything they get, as they screw up the entire business, just look at the Bell 204/UH-1 debacle twenty years ago. Why do they do it? To make loads of easy money!
https://www.faa.gov/documentLibrary/...r/AC_45-2E.pdf