you can think what you want about them, but the fact of the matter is they sell tens of millions worth of stuff on AH every month, and that gil just disappears. you never see any of them with any great new gear, and never see any of them buying anything at AH with that gil, and never hear of anyone crafting any expensive items for them. plus most of those characters are online for an outragious ammount of hours each day(20-24) and always activly doing something during those hours, unless they all have serious sleeping disorders, they are being played by multiple people. that is why everyone believes them to be gil sellers.
unless you can explain where the 20 mil+ that they make every few weeks goes to, aside from being sold through RMT, no one is going to believe that they are not gil sellers.
i really dont have anything against them personaly, but theres too much evidence that they are providing gil to be sold through RMT for me to believe they are storing hundreds of millions on their mules for no apparent reason.