He was saying the vast majority of Apple's (and indeed the computer industry's) users will not be interested in installing another hard drive, video card, DVD drive... even adding memory is iffy for several. These users (to his original point) are not the vocal minority but the silent majority. I strongly concur with him. I've converted 10 families/friends and exactly none of them have asked me how to replace anything in their 2-4 year-old macs. None of them have even mentioned it as a need.
In my extended family nobody but me has ever added memory to a computer or swapped a hard drive (although I have added memory to several of their computers). And in the last few years adding memory to _any_ computer has been really simple. That includes two eMachines that didn't even need a screw driver - all it took was ordering the RAM from Crucial, but lots of people can't even manage that without help. (In other words, RAM won't be added unless _I_ order it and install it).