I've seen this happen on every community I've watched, people join the community forum and get so engrossed into it that they don't notice what's happening in the actual program the forum was made for. Chatting slowly keeps getting out of hand and people slowly forget figuratively what the forum was about, meaning they know what the forum is about, but don't talk about it much. When this happens, the community starts to realize that their forum is, in a matter of speaking, "shattering". Actually, on another forum study I'm doing now, a new group of people have recently joined the forum causing it to sway towards a more on-topic state.