Even without global leaderboards, players can use their stats to make their own leaderboards (I believe this was the case with Halo 3) and even if they didn't stats still lead to whoring
With that logic, this discussion would just go in circles, because even if there were no stats to be seen at all, there are people that would still play like there were stats, or people who keep their own.
No amount of stats or lack of, is going to keep players from whoring - they're gonna do what they're gonna do regardless, just like I expect players (at least on XBL) to treat every match like a TDM, regardless of everything SD is doing to prevent it.
Yeah, people still do stat whoring when games are ranked by other things, like experience. Clans focus on it too much, basing recruitment on stats rather than tryouts. Players focus on it too much, thinking of it as a rating of skill.
I remember in my clan days, I had to go through tryouts. Either that, or I would be playing with members of a clan, who would ask if I wanted to join based on my performance they just witnessed. Of course, this was for RTCW and W:ET - games that had no stats/leaderboards.