the tbc story was actually really bad. Filled with contradictions, retcons, plotoles and completely nonsensical plot beats.
There is no watsonian answer for why Kael’thas, Vashjr, and Illidan became raid boss. It’s purely Doyalist “because we wanted them to be raid bosses cuz that’d be cool” Wow has always operated on rule of cool which almost always negative effects storyline.
Why did Illidan attack shattarath city when they had the exact same goal of stopping the burning legion? Why did illidan enslave the souls of the broken when they were already willingly working for him?
And that’s ignoring the massive retcon that is the Draenei.
At least wrath had considerably less plotholes and retcons.