Good points all. I do know my way around a bike but I think I never really thought about the chain in detail, as I've never before had problems. By bearings I meant the rollers, thinking in terms of engine work I've done where there are bearing surfaces that are not ball bearings.
It totally makes sense that chain "stretch" is not stretch per se, it is an increase in length via the roller diameter wear. Like a true bike geek I will now check out sheldon brown's info on chains...