No doubt we are all aware of a vast pluralism of social and cultural differences, both at home and around the world. What is wrong with relativism, I submit, is that it fails to take such diversity quite seriously or realistically. What doctrinaire relativism tells us is of the unreality of the preconceptions, existing mores, beliefs and convictions of others--and consequently, that it is quite o.k. to ignore this in any majority. One social and cultural configuration, we are told, is no better than any other. In particular, the moral constraints of any particular group are little more than self-serving conventions which can be ignored at convenience. Thus, it appears moral constraint on the part of the advocate of relativism is at best an instrumental affair: what really counts is "playing the game," and politics of various sorts is to trump morality on any needed occasion.
As I see it, this lack of moral constraint is an opening to unholy alliance with anyone, whatever their purposes or means, connection with whom, promises some advance in power. The relativist becomes a hired gun, willing in any situation, in the style of the sophists, to always make "the better argument appear the worse." This is because the purpose of the game is to seek power. Relativism is a "power philosophy" (to use Russell's term) and the tolerance of it is playing with fire. An open discussion of differences is the last thing that is wanted. The followers of relativism become, ultimately minions of the powers-that-be.