also the MC1 era frames (until 1993) were not particularly light. Mountainklein, Pinnacle, Rascal, MC1 Attitude frames weigh 2000grams and more iirc. i think my medium MountainKlein frame with bottom bracket was 2300grams. Pinnacle and Rascal are not much lighter. only the MC1 Adroit frame is lighter with the thinner walled tubes and carbon/boron reinforcements. even back then there were lighter steel and Ti frames but they were much less "stiff".
a big step ahead in terms of weight were the Gradient tubes on the MC2 era bikes. the Pulse frame weighs 1500grams, 400-500 grams less than the Rascal which it kinda replaced. and even that is not overly light compared to current frames.
cheers, carsten