You didn't get enough gold to do that in real games. You could do it in yoloqueue, but you weren't going to get the 6-7 lane kills you needed to make up for the garbage Season 2 jungle income to actually build full carry.
People have always played Lee Sin jungle, but they've generally played him as tank or even support (Sightstone + Aegis) builds rather than carry. Carry Lee Sin was just a solo queue thing, like Jungle Shaco (mad props to Rainbow Thugs). Even now, at most he's a Lizard Elder + LW -> Full Tank sort of guy.
I mean, even at the height of his power his ideal scenario was that you dove into the enemy team, mostly-assassinated the carry, and then didn't do much of anything. He's always been a sort of half-ass assassin due to only having his Q once his ultimate is down, compared to assassins like Ahri who could do in-and-outs and burst another person as soon as their non-ultimate abilities came off cooldown.
Carry junglers are things like Kha'Zix and Evelyn. Things that can (at least hypothetically) put the entire team on their back, not fire-and-forget human rockets you launch at one of the enemy carries and then kiss goodbye (Lee, Skarner, etc.).