The other thing is, if you are going to participate in a public forum, why would you put another participant on ignore? If you write a good post and the ignored person provides a good counter argument, maybe you can provide a good or even better counter reply. But if they are on ignore you couldn't counter it, as you couldn't read it while everyone else can. So in the end, everyone else thinks you've got nothing in reply..who's at a disadvantage?
