Popcap and reduced manpower income are there to give an opportunity to the losing team to come back.
Maybe add that you can get above 100 pop, but since you need manpower to reinforce reduce manpower income about 75% when going above 100, so you have to have a haevily mechanized army and are not really able to rebuild losses until you reach lower pops (at least 70-80 to get actual manpower) but if you keep your stuff alive you will be able to boast a massive unit count, whch u still have to micro well so not to lose a ton of units/models to keep it (up)