I tend to agree with you. It seems as though they have embraced the mixers advertising on their platform because it helped bring a new wave of members to their forum. They also would probably ban mixers if they thought it could bring negative attention to their forum.
In fact after the mixer ban here, I believe they tried to make it more accommodative to the new users who were joining it. It was an opportunity to increase the traffic over there and i think there was a change in the traffic stats in the following months.
The only way I would see them banning the mixer would be on the request by the law enforcement or some lawsuit threats.