It is more comparable to time than anything else i can think of. Even the most skillful players have difficulty playing a CP-denying strategy. What is the point of having something that cannot be controlled, denied, earned, spent and something increases almost unilaterally for both players?
It is not time literally;It represents the progression of the overall battle. But why is it important for call-in units?
Players decision and performance has a major impact on CP in 1vs1 games. The impact becomes less in higher modes where the inflated economy makes teching allot faster.