I have one poster on ignore-- Dutchy's offspring. If you saw the harassing, intimidating and obnoxious pm's from the guy, you might understand.
BTW, ignoring someone instead of fighting with them is not intolerance. He can say whatever he likes, and like a coward, I am sure that he potshots me on a regular basis even though he knows that I will not engage with him. Telling someone to shut up or to stop arguing their position is intolerant. Maybe you didn't understand the term?