It's human nature, I'm afraid. One person takes the mickey and others come on. trying to make a cleverer post. They are the only ones who do not realise that they are not very clever, at all. Others are drawn in and the whole thing becomes a shambles.These threads have to be monitored constantly to make sure that that does not happen.
It's not a conspiracy, it is a move by the mindless to try to post something clever.
I'm not excusing myself from this, either, although I do my best to be fair.