I'm not sure what your objection here is.
* If you field 50 peasants and 50 guards the guards will get half the
attack attempts and the peasants will get half the attack attempts.
* If you field 100 peasants and 50 guards the guards will get 1/3 the
attack attempts and the peasants will get 2/3 of the attack attempts.
That's true under the current system as well as under the 4:1 rule
system. The only thing the 4:1 rule can effect is how many attacks a
side gets during the battle.
Here's an analysis of 5 knights + N peasants vs. 1 dragon:
# Peasants Current 4:1
5 79% 57%
50 99% 73%
In both cases adding peasants improves your chances of winning the
battle.
-- Scott T.