Absolutely, you cannot subject your inverts (clams, corals, shrimp, crabs) to hypo. It is only practical in a QT and only for a display of FISH ONLY. I don't agree that there will be dormant cysts. They live out their life cycle just as any other organism, although they can live in/on a fish and never explode because of the immune system of their host. As a matter of fact, if they have no host they will eventually all die off. It is new fish and water that continually brings them into your system.

I would rather quarantine the fish myself. LFS handle too many fish, too fast. They keep their systems connected and ich is rampant within their systems.

I will agree that outbreaks of ich are not usually seen in the wild, but ich is not rare there. It is just that when a fish gets sick it is usually eaten, if not by a predator then it is killed by its own kind.