Cons can build sandbags and have 6 men which is enough to stall till 4 (i did that 8 games in a row)
Also p4 gets actually hit by ZIS because of the target size
pure hit chance of t70 at max range is
72%, pure hit chance of p4/t34 is
80% (18 vs 20 target size). If t70 had target size of 14 that would have been a somewhat valid point.
EDIT: the other side is speed. If microed t70 is harder to hit, because it can escape from the cone of fire more easily. But mobility alone does not outweigh the difference in health and the fact that if you faust a t70 it is much more likely to die.