It's a genuine problem and has been growing gradually worse for a while. I think the cause is simply growth. When a good community grows, it becomes worse in two ways: (a) more recent arrivals don't have as much of whatever quality distinguished the original members, and (b) the large size of the group makes people behave worse, because there is more anonymity in a larger group. I've spent many hours over the past se…
Making it invite only would have (IMHO) improved things a massive amount. Have people do a test to gain entry.
Any community that is free and open will just deteriorate over time.