Well, on the retail, to get 20 character multiboxxing, you need to pay 20 times, which means a big big amount of money (to me ofc, some people are rich in this ****ing world) and this is only to be able to play 20 char, not having them with BiS stuff. Here, you can create account freely, you can buy the stuff, and something more important : the game isn't upgraded with patchs and news content like the retail which make your BiS stuff useless after sometime.
Mbx at this point (about 20 char) is just a ****ing joke that only private must know, and if it was happening on retail, Blizzard would certainly do something about it because this is a no-sense of what the game is, the gameplay is (alterac valley, a fight for the tower and kill the boss, if long the renforcement ? Hey i'm mbx, i **** you blizz and your gameplay, i put my big *** just in front of the boss room and i wait and i ruin the 40+ other player experience).