Oh not the b****y clique accusation again. No, there are not cliques. It is possible to have the same opinion on a subject as someone else without being a clique.A clique keeps out other people. All threads are open to all posters who can add something to the conversation.
There are threads where people are discussing personal problems with others who are experiencing the same thing, and they don't take all that kindly to anyone coming in with quick answers who doesn't know the back story.
There are also people who have been here forever, are familiar with the personalities posting. They read posts about those who are being attacked for something, and comment that X would not have said Y to be deliberately nasty, as the attacker has claimed.
There are people who have met in person, have known one another for years and - of course - if they see a friend being unfairly criticised, they say so.
If you have something to say on a thread say it. If you don't like what someone has said, reply (politely) or report the post to GNHQ, who will act as seems best.
As for names disappearing, people come and go all the time, not usually because they have been "bullied" off. Try PMing anyone whose posts you miss, to see if they are OK. Chances are they are on holiday, busy with family things, or just doing something more interesting. This is only a virtual community, after all, people have a real life too.