The funny part about "hit points is not meat" (which I know is the intended explanation for them) is when you look at two factors: one, Constitution affects hit points*. Two, some classes get more hit points than others. Why?
I mean, really, think about that. Why does a Barbarian get more hit points? Because he's tougher, more rugged? Is he luckier than a Rogue? Have more divine protection than a Cleric?
*Obviously, hit points are at least partly meat, and that was never really debated. It doesn't seem terribly strange now, but in AD&D, when only certain classes could claim the benefits of Con above 16, it was pretty odd. Then you toss in healing spells being called, well, cure light wounds or healing word, as opposed to "boost morale" or "rally".