Take BW. SC2 can be said to have 3 main differences. Somewhat different units/abilities and macro mechanics, both of which are irrelevant.
The third is mobility mechanics. Warp in for protoss, creep for zerg (although zerg units are faster overall than terran even without creep), but nothing for terran.
Remember that this is BW. Let's say we take BW, put in warp in and creep tumors where zerg units move faster on creep. Would BW be balanced then? How is the current situation any different?
That in itself I do not see a counter-argument to. Add to this the fact that medivacs are slower in sc2 than dropships in bw, that stim is more expensive in sc2 - and suddenly it's three times as bad.
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