In fact, CODGUY is right. T-70 come at 9 minute of game, while 1-st p4 at 14 minute (you could get ostwind at 13 minute or stug at 12,5). Default fuel income in 1vs1 23 fuel per minute (when map equally divided between players). Soviets T4+T34 costs 90+90=180 fuel, t70 cost is 70 fuel. If you build t-70 you need wait 8 minutes, until you could get 1-st t-34. Without T-70, you could get t-34 right in time when 1-st p4 will arrive or little bit later (if you have at-nades and molotovs grades).
It's just question about standart builds. Current soviet meta - T-70. Without T-70 you could meet early t-34.
Actually CODGUY is as much as half right. SU had a better early game offensive roster, T70 can make a lot of space and force OH to adapt instead of hoard fuel. I find sad that t34 comes so late because it should be the first medium landing the battlefield when rushed.
If a faction can and must impose pressure to win, not doing so can be considered a mistake.