I am a beginner and I am very good with computer just on small maps population 25 because the population is ending and it does not grow and you can calmly play. You do not have to be as fast as in the game of 200 population?
I remember replaying the campaigns and liked the 'limited' population of 75; it really adds a layer of strategy in the sense that braindead spamming isnt possible, and you gotta balance your economy very well. I cant remember ever seeing a multiplayer game with less than 200 pop though!
On most maps most players don't reach the 200 limit before the game is over. Maybe half of them. If everyone managed to reach 200, it would be a long game. But you already attack with 30 or so and constantly gain and lose.