I've never heard anyone who actually played and raided with any seriousness in Vanilla ever say that. Paladins were so ridiculously better for your raid than Shaman that with the exception of Vodka and Nihilism(and I'm fairly certain if faction changes were allowed back then guilds like those would have faction changed) there were no serious Horde raiding guilds in the world first race. It was a nice idea in theory to give the factions something exclusive, but in practice it was a complete and utter disaster. It is literally impossible to 100% balance two different classes without making them exactly the same. Just look at the current state of the racial bonuses. Horde bonuses are 1-2% better for PvE and there was such a massive influx of progression raiding guilds feeling like they had to faction swap to keep up that Blizzard said they considered revamping all of the Alliance racials to make them more attractive for raiders.
At best you could get away with how the Old Republic handles it. A Sith Juggernaut and a Jedi Guardian or a Sith Assassin and a Jedi Shadow are exactly the same class with exactly the same abilities, just with different names and animations to make them feel more dark or light side. But even that is a waste of developer time.
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There was no "bloodlust problem". Bloodlust and Heroism were added to the game at the same time.