Imagine there being.... hundreds of dps and just few tanks? I was looking for a healer for +16 SD today, in about a minute there were like 20 in the que. DPS are 5x of that.
Nothing to do with the players - just lack of tanks, why? Next expansion, tanking is stressful for a lot of people who are not familiar with dungeons plus you have to be really on the edge or you get killed very fast.
Create your own group. I don't really get the complaints about "no one invites me"