There can be alot of reasons people level slowly. I have alts that I just occasionally play on when I am really REALLY bored.

But what I find more interesting is the 'people who keep tabs' comment. There are people who are doing the same with me. Every so often I recieve some random tell continuing some conversation I had many days before that I barely recall. Or they start out, "hey, remember me?" And I'm too polite to say, "uh, no." And people say some of the most random things to me. The other day I received a tell, "hey, remember me? We were questing in TM at the same time. I just ding'd 70! (I'm level 44 now) I guess it's slower going with multiboxing?"