I can't recall any clear and logical reasons why it might actually be necessary.

Yes, you are right, Kevin. My apologies. The clear and logical point was that there are times when reasoning just does not work and I actually gave a choice there - Either walk away or let your feelings be known. Why some people make one choice and not another is not logical and often unclear but to let, for instance, bigotry, stand and not do anything about it is a very difficult thing to do. So, clear and logical was the wrong choice of words. There are times when no amount of reason or logic will work. In those circumstances it may not be necessary to resort to invective but it is sometimes right. In my opinion that is.