Yeah I read that not everyone has Ich in their tank and that it is an old wives tale.
Maybe it came about because there is no way to know if a fish has it so they just figure everyone has it.
I also read this from a post on how to treat ICH.
I have tried this and it works everytime... First step is to get a plate. Using your fish net, remove one of the infected fish from the tank. Gently lay the fish on the plate. Most fish will calm down and stop flapping around in about 30 to 45 seconds. When you fish is nice and calm, using a pair of Revlon Diamond Grip Tweezers, gently remove all those pesty little ich parasites. Then turn the fish over and repeat. Return the fish to the tank. It may gasp a few times, but it will be ok. Just simply repeat this step over and over on all your fish untill no more ich is visible. Wait a few days, then check fish again. If the ich returns, just do it all again. If you happen to accidently pull off a fish scale or two when removing the ich, don't worry, it'll grown back eventually.