Strategic mistake. But we are not law enforcement to say having them here could be better to keep an eye on them all in one place instead of having them go elsewhere scattered.
The bottom line is they will not find any bigger Bitcoin forum than Bitcointalk.org. They can advertise their mixers somewhere, on other forums, darknet but they will miss this forum a lot.
Will it come to a time of KYC-mixers?
It sounds weird now but maybe in future, it will happen and with KYC, mixers will be allowed by laws. The point is to avoid criminals to use mixers, not good people who want privacy to use mixers.