I am still not understand how both players don't get better. The one being coached figures out a line of attack/defense that is good against their opponent. He will use this information in the future to not lose to a similar strategy. Likewise, his opponent must figure out how to react to the counter-attack. He also figures out different lines of attack/defense, and this will help him in the long term as well. What's the point of any competitive game? To be the best? How do you become the best? You familiarize yourself with as many different situations as possible and learn how to overcome these situations. You want to be able to succeed in any environment. Coaching helps short-term, but I would argue that it's more beneficial to the long-term. This whole thing is just simple theory for competitive gaming; I honestly can't believe nobody sees my point (except for KB, but even then he doesn't really agree).
Sovereign, I'm not a brawl player (melee/mvc3 player), so I doubt I could beat you in brawl. Even then, your coaching argument is incorrect there as well. You would likely win based off of your own talent alone (although you did get 25th, kind of a tempting offer . . .), and coaching would more than likely have nothing to do with it.
Basically, your initial assessment of "I lost because the other person was coached" is a very incorrect statement. You lost because of your own fault. You weren't familiar with a different line of attack that your opponent may have had, and that is your own fault. You are always the one responsible for your losses, not another person. You're the one that controls how well you do and how you will react to your different opponents. Of course, this is all theory-based. You cannot blame your losses on other people.