In recent personal experience, it would transpire I am not the only member in recent weeks, to receive emails (outside of the PM system) with messages about being "unwelcome"...
Really :-? i don't know what happened the other night, and I don't want to know but I did not realise there was another side to oof 
Though I have not done it, I might be tempted to contact a member by other means to express an opinion, if for example I thought tey were out of order, but in no way is it my place to say who or who should not be a member, or even that they are unwelcome.
By the very nature of people we are all different, but we need to recognise that and accept it. Life is too short to be falling out big time. 
I am talking more the other month, than the other night.
It wasn't a case of falling out, it was just a case of an entirely nasty email, simelar to what Kris has described
Only difference being, the email I recieved was more related to my personal circumstances, rather than forum posts.
Unfortunately there are some issues. I just hope in light of recent changes, things will cease to occur...