My position is this: there's no 'tank' archetype, just because, all members of the party must do everything in their power in order to improve their defenses, i.e. be 'tanks'. This is the reason why constitution is so important and some people despise races that lose con, such as most elves. Having a single party member with awesome AC & hit points, doesn't mean that all other members are covered.
...
Disagree. And, this seems to be based on a fallacy -- that people have to do everything in their power to improve their defenses.
Premise: the game involves opportunity costs. You have a limited amount of character resources -- every gold you spend buying a defensive-oriented magic item (e.g., Third Eye of Clarity) is another gold you can't spend on offense or utility. Every feat, spell, action, etc. is the same.
In many cases, it is more efficient for character/build Alpha to acquire a defensive ability than for character/build Beta to do so. A cleric who has a remove paralysis handy, a psion who takes damp power, and a spellcaster who has freedom of movement available can all be taking advantage of that. In some, surely not all but we're talking at a pretty extreme level of generality here, it's easier for the psion to mitigate "area effect blasty spells" than it is for each character to do so on their own.
That's the core feature, metagame speaking, of the Tank. She stacks defensive abilities and resources, somehow, freeing up the Hood or the Striker or the Glass Cannon to allocate their resources somewhere else. Now, clearly the extremes are bad: Captain Invincible but Utterly useless is bad, as is Major 10,000 Damage But Made Out of Paper-Mache. But, that's the basic idea. A Tank's role is to mitigate, prevent, etc. harm to herself and the rest of the party. With savvy players, this frees them up to expend their resources elsewhere, whether it be character build resources or in-combat tactical ones.
The overlap between battlefield control is made pretty obvious on this formulation. Just as solid fog or web deny enemies the chance to really hurt you where they would like (e.g., protects the relatively low hp god wizard), the tank is designed to do the same through a variety of means.
I don't know if this rises to the level of an "archetype" b/c I admit to not really knowing that that term means. Is it a concept we can wrap our heads around? Yes. Can it be built effectively? Certainly, I mean people on this board can make anything pretty badass, and this one isn't exactly rocket science. Is it "optimal?" Probably not. Although that also seems besides the point -- I haven't played the toughest character I could make in a game for at least a decade. And, if we were aiming for the bestest characters evar!! we'd all play Pun-Pun or Omnifiscers or something every game.
Note that this understanding of a Tank works best in troupe play, but that's the norm in D&D. Otherwise, you're just someone who stacks defensive resources. That's not necessarily bad or ineffective either, but it's hard to talk about that as a "role."
