Is it wrong to run Castrum Abania as a tank at ilvl 272

[Nestama]

Except it pretty much is. Some people are convinced that 4 man dungeons are so difficult that doing it with anything less than the very best (because i270 is not much less than the very best) makes you a leech to your party. Why is this true in Abania at i270 but not true in EX dungeons at i380?

Where abouts? All I recall what has been said is it just makes things obnoxious for everyone involved if the tank is in i270 gear, as they now have to adapt to one person who may or may not know how to play the Job at your skill level (you've claimed it can be done, but that's just you and whoever else says they've done it. I gave my experience and you said that's because the tank was bad. No duh they were bad, however they would have stood a better chance at surviving and preventing a wipe to trash mobs if they were appropriately geared).
EX Dungeons are tuned to the minimal required ilevel (currently i340), whereas levelling dungeons appear to be tuned to the required level and the gear it expects you to be wearing.

Also i370 was the highest ilevel before 4.4 dropped, so...