I suggest to read the Threadgill Sensei "Psycho-Chemical Stress Conditioning in Budo" articles (Part I
- Part II
) where the issue is much better explained.
From military training forward, I do not question the need to train for the situations that we may encounter, which includes full stress from the individual level right through the "fog of war" at the command levels.
However, I liken the use of sport to accomplish this in aikido to the teaching of super-efficient striking in karate to teach the way of not fighting: Until you deeply understand and integrate what you are practicing, you are prone to act in a way contrary to your art's intent.
I suspect that a fully "evolved" aikidoka can maintain his mind under competitive situations as well as in any other situation. This to say that he can deliver a spontaneous, appropriate, "clean" attack or response---where "clean" implies an action unencumbered by any thought
rooted in the competition or in anything else for that matter. But why begin training in the duality of competition and then hope to break from it?
Without the "clean" mind (from training infused with an understanding of masakatsu agatsu), the spontaneous and appropriate martial resposne (takemusu) is hampered.
My ideal for training is that one can both attack and defend purely, without any intent at all. Someone cuts with the sword without rising hate or fury, and without rising fear of hurting your training partner---he simply cuts, fully present in the act. The other person simply defends, without holding thoughts of love, protection, choice, or any other---he simply responds, fully present in the act. Within the encounter, there is no notion of winning or losing, let alone scoring a point.
This can be trained, and Threadgill's PCS can be induced, without introducing competition, which still seems entirely contrary to the philosophical underpinnings of aikido.