That is true but can also be said about all fish sold at a LFS. Almost all the fish available with the exception of some tiny fish or seahorses, should live 10-20 years. If your fish are not living that long, you are doing something wrong. That includes copperband butterflies. Clownfish live over 20 years as do angels, Gobies should live at least 10 years as will coral banded shrimp ,urchins and crabs. Mine do, and if mine live that long, so should everyone's. If not, something is wrong. The fish want to live, and if they don't. it is not the fishes fault, but ours. It is not usually the LFS fault as he has no say as to how the fish were caught or shipped. But if the fish lives a few weeks or months, and dies in our tank, it is our fault. I think the biggest reason fish don't live their normal lifespan is their captive diet, which in most cases is just wrong. We tend to feed what is easy, not necessarily what the fish needs. Fish don't need a variety of food, they need the food they were designed to eat. Copperbands in the sea eat live prey. They don't eat pellets, they eat mostly live worms and tiny shrimp. That's what they should be fed "every meal". Mandarins also need live, tiny food, not pellets or frozen Mysis. They need pods or baby brine shrimp which are about the same thing, but they need it "every day" and in the case of a mandarin, they need it constantly. They want and need to eat a pod about every ten seconds. If you can't or won't feed that way, you will kill that fish and it is not the fishes fault. I find copperbands and mandarins to be easy fish because I feed them what they are supposed to eat and I don't try to "teach" the creature to learn to live on something else. If I can't feed it properly, I don't buy it.
I don't keep orange spotted filefish because I don't want to feed it coral polyps, I also don't keep Moorish Idols any more because I don't want to collect the sponges it eats. But the last one I had lived five years until I killed it in an accident while I was away. 5 years stinks but for a Moorish Idol, that is practically a record. To learn what a fish eats, I go to the place the fish lives and I spend time with it underwater. I dove in Tahiti to learn about Idols and I was in Hawaii for the last two weeks swimming with them and long nose butterflies. I realize most people can't do that, but if someone with direct experience and a fairly good record of keeping those animals records what they need to live long, maybe we should not keep them if we are unable to feed them correctly.
Just my opinion of course.
Last week in Hawaii