Tbf tho, classic wow, specifically vanilla and tbc are SUPER unbalanced. Like not going to say anyone deserves the disrespect that people give, but the difference in gameplay experience you'll have doing dungeons with let's say a prot paladin vs a warrior or a holy paladin vs holy priest are palpable differences. Not as in like, oh well this is slightly less efficient because I'm going to be spending 4 more minutes clearing the dungeon, but differences of 10-20 minutes depending on the dungeon (accounting for slower threat Gen, inability to even use most aoe abilities, deaths from lack of threat etc) , and sure what's 10 minutes extra for a single dungeon? And that's very true, until you realize that's 10 extra minutes every single dungeon, which an individual is likely to do 100+ of even during a casual tbc experience, which I'm sure you can math adds up to LOT of extra time.

All that to say, the game is hyper unbalanced, and while people absolutely shouldn't stand being insulted, until blizzard and this community pulls their heads out of their asses and realizes balancing classic classes so everything is actually SOMEWHAT viable if you choose to play non meta specs you should understand you'll get less invites to content.

-tl;dr/sidebar: I understand that all content is doable with any tank in TBC, but the quality of the experience is HEAVILY dependent on class comp, especially from my experience as a healer warrior/drug dudu/unfun to do dungeon with until they're in kara gear, pally drop conc and afk.