That isn't tanking, that's crowd control. What you are doing is attempting to redefine what tanking is in order to prove yourself right. Tanking has never been about locking down foes with ccs and stuns. If that's true then I guess rogue in wow by that definition is a tank since they stunlock targets. To go further, a role's definition does not change depending upon the game mode.

Perhaps this would broaden your perspective of what it means to be a tank, since the role does not change in any game:

A tank is a style of character in gaming, often associated with a character class. A common convention in real-time strategy games, role-playing games, Fighting Games and MUDs, tanks redirect enemy attacks or attention toward themselves in order to protect other characters or units. Since this role often requires them to suffer large amounts of damage, they rely on large amounts of vitality or armor, healing by other party members, evasiveness and misdirection, or self regeneration. http://en.wikipedia.org/wiki/Tank_(gaming)