I just wonder why these posters have so much difficulty in joining in a civilised debate!

I don't think it's so much that they find it difficult, I think that they just don't want to. I suspect that there are people for whom the idea that people who disagree with each other should express their differences without making personal attacks is seen as an offensive idea - hypocritical, dishonest, lacking in spontaneity, that kind of thing.

If you think that way I suppose it could give rise to a wish to break things up, and a feeling that that is a righteous thing to do. In a way it's a kind of iconoclasm. The very term "civilised debate" could be like a red rag to a bull. In a china shop.