That’s not true for a barb. You can pretty easily get defense high enough to matter in hell.
I have 3794 armor in nightmare with just shout, over 5k while using concentrate (though I normally use whirlwind instead, concentrate vs bosses and tough uniques).
That’s with a chest armor that only has 240 defense (a lionheart templar coat).
When I swap that out for Duress diamond mail with 1500 defense that will be an extra 4500 armor after shout, not counting concentrate. If you really wanted to go crazy for defense you could get a defiance merc but imo might is better since you can have pretty high defense with just shout.
Edit: I didn’t count iron skin either for the diamond mail defense… its going to be such a huge boost heh. Cant wait to hit the level for it.
Second edit:
As an added bonus, you keep your defense rating while whirlwinding around, which is actually faster than walking. If you go frenzy barb even walk speed will be so insanely high you will have a hard time controlling the char. With 1 point in increased speed you get a good chunk of faster run walk after +skills as well. Throw in some nice r/w boots like natalya and your walk speed is pretty solid to move around in combat with.