It's because of how easy the game is to play and how well it can be played by one person (I'd say 75% of all quests can be solo'd at a level where experience gain is still worth it (this excludes doing a level 10 elite quest at 59 😛)). I know I solo all the time because of how easy the game is... it may sound odd, but that's because the ease of the game also breeds people that don't know how to play. This past weekend, I saw a hunter begging for help constantly for even the easiest of quest ("For Lost Honor" being one of them... you kill a water elemental or two and grab a flag in the water. Not hard...). It just made me sigh.
I really think that number might be off... I just don't think that's truly "active" accounts or accounts that see decent play time (factors out the incredibly burned-out people that barely play or only play to talk to people).
