Warrior was the preferred tank without a doubt.
Does it mean others were totally useless? No. But certain things people don't think about a whole lot today mattered than. Like a prot pally? Out of mana in like a minute. Required things like spell power to generate worthwhile threat for that minute. To get spell power gear you don't get defense/dodge/parry which makes you get chucked. So a catch 22 in a lot of cases.
Could you tank 5 mans and such with it. Yeah. Just a lot of drinking for that mana. It just isn't optimal.