Happy 4th of July, Jun!
By training with the "real" meaning of competition and the intent to transcend the fear or worry of "winning and losing" we have the chance to actually succeed in this transcendence.
I think if we do not have a "competitive attitude" there is no real chance to grow. However, if we have, as Roger says, taken to using the concept of "combat" while using the word competitive, we just muddy the waters. We are then trying to eliminate something that is necessary to succeed in the practice.
I think there was a mistake made in translating M. Ueshiba's teachings by using the word "competitive" as meaning a zero sum activity where there is a winner and loser. Of course this is paradoxical because most of us for a long, long time feel deep in our guts that we "lose" every time someone makes a technique on us when we don't expect it, etc. This is why the transcendence is necessary. Winning and losing isn't important ... until it IS important! We must know the difference.