You really didn't play WoW back then... did you? People had TWO years to figure all this stuff out. We had plenty of tools and addons. DBM was a thing, stat weights and theory crafters were a thing... all of this stuff existed. No one is going to find some magical rosetta stone that suddenly shows us the secret door to OP play in Classic.
Bosses had three distinct variables: 1. Did the tank have enough health, 2. Could the healers keep everyone up, 3. Did the DPS do enough damage fast enough for 1 & 2 to matter.
There is no OP gear that is suddenly going to spike your DPS up, or give the tank a massive health pool or give healers this endless pool of mana.
People will have to learn how to downrank spells to conserve mana, dps is going to have to ACTIVELY watch their threat because you could easily pull off a tank... that's just how it was. Look, I'm not trying to be mean or snarky here... I am saying that your view on this is very wrong IF Classic is released truly as it was.
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Also, lest I forget... this is FORTY person raids. Not 10 or 25... 40. It's like herding cats to be a raid leader back then. You've seen the "MOAR DOTS" video with the raid leader screaming -50 DKP? That's very exaggerated... but that's kind of how it was.
And then you have TWO pieces of gear on average from bosses. And you use that to gear your raid of forty people.
It's going to take time and will NOT be piss easy