"Nin is the only real tank right now."
I'm sorry, but what?
A mnk can tank just as good. /war or /nin, doesn't matter much, it all depends on the kind of nm you are fighting (if you need to backtank it sometimes etc).
War can also tank just fine. More dependant on a healer, but it can outDD most other jobs and hold hate just fine = i.e. war can tank.
Examples? Duoing Orthrus with a friend - he's mnk/war, I'm whm. Piece of cake. The most dangerous move Orthrus does, Acheron's Flame, will kill a nin just as easily as a mnk. Actually, it's likely to kill a nin faster than a mnk or a war. Also - duoing Isgebind with a friend - he's war/sam, I'm whm. A lot more efficient than nin + whm simply because war kills it much faster.
I'd go as far as saying mnk and war are better tanks than nin for some of the harder nms (btw not saying Orthrus is hard!).