Because the multiboxing that's going on now isn't the same thing as it was in the past.
I used to multibox, I ran a 5 account team in dungeons in Wrath/Cata. What it is now is not what I was doing - it's clearly a problem with mats and camping spawns so nobody can play in an area. And, seeing how limited flowers and ore are in the SL beta, it was going to be a MASSIVE problem.
I used to be very mindful of the rules back then, because the token didn't exist, so I was paying out of pocket to do it, so I wouldn't dare do what the MB/bot farmers are doing now. They have minimal risk, financially, because they can fund multiple accounts farming zones.
Watching the videos of what's going on in the live servers, I'm not shocked by this in the least.