well, when you are warring you are either A) being chained or B) not being chained (at the level greenie plays at)
in situation A) forts aren't useful, as you have been chained and have no def left anyway right? And in B) they are not useful as you are not being hit. They only help when they bring you to enough def for unbreakable, or for OOW random hits. The TGs are of help during both scenarios.