Yes the groups for specific types of men have not really took off.
Most people just set the computer to show recent posts from any group. So it doesn't make much difference where you post. For nearly all men what your race is or your gender doesn't make a difference to how you will be treated. Though it does make a difference to how likely you are in life to need prostatecancer UK.
Perhaps the only exception being post op transsexuals who may face some different issues.