Perhaps all intolerant groups harness violence, but it is clearly not a required element. They could easily substitute it with social stigmatization, and achieve a similar effect. Many religious people today will disown a son or daughter for coming out as gay. Were there no legislation stopping this, I imagine the same people would refuse to allow gay people into their businesses. If we were able to guarantee that all violence would be punished, the intolerant groups would quickly adapt while remaining intolerant.