My FC has literally more Tanks and healers than we can party with. We always have tanks for coils and any HM primal, and only ever so rarely do we have to use the duty finder to get a tank.
I for one dread the duty finder. Everyone's main instinct seems to be 'blame the tank if I die'. Two days ago, I had to do a WP DF run just cuz I logged in way early. We reached the second boss, where he spawn adds and can follow a random player, and the adds will follow that same player. Silly DPSes just stood there and got aoed to death. First thing they did? "Tank hold aggro omg."
Tanks are there, in fact I find a lot of them shouting for parties in Revnant's Toll. Just go there and get one, don't use the duty finder. Most tanks and healers avoid it.