I was recalling the way it was explained to me in 2005 and I was not aware of a change. Please excuse my ignorance.
.It's at least the 5th time that I pointed it out in a "what's traffic and how does it work?" post and someone then counters with the "official" explanation which as far as I can tell simply isn't accurate (anymore) and it gets rather tiring to do the same dance over again each time because people don't use search.