What has saddened me, and yes, irritated, is when (often) new members seem to set out to cause division - either in a passive/aggressive way so that nothing they actually say seems that bad, but the effect it has on the site dynamic becomes unbalanced. And the less subtle, aggressive, hostile type who clearly cares little for the feelings of others. I don’t mean that to sound cliquey but if you join a group you don’t do a “Meghan” and put backs up from the word go, being critical and expecting everybody to see things from your point of view, do you?
There is often a pattern as others have noticed and after a bit, things settle down a bit, but feelings get trampled in the process and there are frequently casualties. You learn who your friends are and who to perhaps avoid in the future.