I laugh when people compare other MMOs to WoW and say that it has 5 times as much subscribers or more than any of them.
Why are you ignoring the fact that most western MMOs don't launch in Asia, which is where more than half of WoW subscribers come from?
If you want make a rightful comparison you should only consider the regions where both games exist.
WoW has around 3-4mln subscribers in EU/NA. Yes, it's still more than any MMO here, but it's not 5 times as much.