I did, first on my Mage. Had to hand out food and water to people individually, and later, Healthstones on my Warlock. Also, summons and farming shards. The fight was a pretty big deal, lots of preparation involved for raiding in general back then.
Of course as a Mage, even if you were specced for Fire you had to spam Frostbolt because of how damage types and immunities worked back then.
I actually remember watching a video of 40 Frost Mages killing Ragnaros, it was a sight to behold.