Actually yes. And not just that, I understand it doesn't work on bosses at all - or even champions. So yeah. Could have sworn I said that. Oh, I did.
But regardless, the point is that he has stacking damage amplifiers, and complete invulnerability attacks. Plus 'walls' and healing abilities. That means his survivability is absolutely amazing, and the team can take advantage of the tactical and damage amplifiers also. So bosses will go down lickety split.
So yeah... near-perfect tank.
And I see a lot of gold runes in his future to ensure that he stays invulnerable constantly.
You forgot to say squishy.
The monk has arguably the worst survivability traits out of all the classes, or the least consistent anyway. His only unique defensive traits are; +healing which requires the monk to actively make use of, +dodge a very binary defense you can easily get screwed by RNG, and +lightning/fire/cold resist only improves his defense against SOME spells.
While the WD isn't much better but his defenses are more passive and often definite, not to mention he is designed to be a ranged character using summons and other spells to keep the enemies back.
The wizard has quite the selection of good traits, several that will amount to a large boost in armor, magic damage reduction, melee damage reduction, missile dodge. Again the wizard is primarily a ranged attacker, excellent maneuverability and control of the fight helps to protect her.
The barbarian, well I've shown you a potential build for him that jacks him up on so many defensive traits that he actually topped 30 spent points before he even had them all, or any offensive ones for that matter.
I just don't think the monk is going to be able to remain invincible all the time while dealing out massive amounts of damage and debuffs like you expect him to. His defenses are going to lapse and there will be times where he is extremely vulnerable, an inconsistency that the barbarian doesn't have. If I learned anything from my prot warrior on WoW, it's to never rely on defense that isn't always there. Armor and health were king because they always protected you, sure avoidance is great and it can help you survive things you might not have but there's a good chance it'll fail you.