Also, keep in mind that the damage for infantry is calculated based on the number of soldiers in the unit. If you combined the platoon into one card, it would be a unit with 4/4/0 damage and A/S 8/4. Killing off troops would not change its potential damage like when you have separate platoons.
Additionally, there's times that you would rather have 4 attacks rather than one attack with a high damage value.
Plus, 100 soldiers would be a mob with a 4 inch base LOL Not very practical for movement.
Now if you're talking about one card with multiple squads, so you can track the damage separately, that would work. It would require some photoshop, but easily done.