I've heard it too - but quite frankly as long as you take care of the helmet and it's stored inside I'm not sure why you would. I have one where the outer plastic has started to crack and I've thought about replacing. I just replaced a Garneau last week but that's because I had a spectacular dismount on my night lap in a 24 hr race and hit my head on a rock cracking the helmet all the way through.

We've got a couple that are over 10 yrs old that kids have worn and other than some fading I don't see anything wrong with them.