I agree more or less with what you are saying. The "name" should only apply if it can be traced to the "namer". That being said, the original coral, Let's say the purple monster for example, was collected in the ocean from a mother colony. I find it hard to believe that the diver only collected on piece, and never went back. It is well known that the divers in the various countries that export corals, work certain areas of reefs, and know where certain corals are likely to be found. If they find a patch of Micromussa or a huge thicket of blue tort, they will mark the coordinates, and work the area on a regular basis ( hopefully not overhavesting, but utilizing a sustainable resource). That being said, logic would dictate that there are in fact more colonies of the "original" Purple Monster out there.
A murky situation for sure. My policy is, if I like a coral, I will pay the price being asked. I have many of the name corals that I paid a premium for, and many lookalikes that didn't cost near as much. Most people who see my tank don't know which is which. In fact, some of the most sought after name corals, like the PM, and the Pink lemonade, rarely garner any attention in my tank from visitors.