Historically, many martial arts have tried to ensure their continuation by becoming a sport once the conflict or social condition that lead to their creation was past. Although this has proved to be a very successful strategy, no one wants to take part in, or watch, a sport in which one or both of the contestants die within the first two seconds. Therefore, a set of rules have to be introduced to make it safe. Which, when you consider the essential purpose of martial art, is a bit like a system of gardening that ensures nothing grows. Inevitably the style will change to match the rules, often becoming unnecessarily complicated, because when a simple move would hurt or kill your opponent, your need a more complicated technique that will achieve victory harmlessly. You will hear participants in some competitions say, “I could have won in the first seconds if I’d been allowed to do this or that.” Sometimes a slimmed down selection of techniques, for example boxing, where the gloves limit you to only punches, means that victory begins to depend much more on fitness and strength rather than just skill. If we wanted to train people to take part in tournaments, we would have to miss out many of the most effective techniques. It is not uncommon for people to train to a high level in some sport styles only to find that when they get attacked their skills are of no use, because no one showed them how to win a fight, only how to keep a fight going for minutes without anyone getting hurt.
With that said, many tournament styles are exciting sports in their own right, and often they give great physical confidence too. That translates into an ability to stay calm and in control in the face of aggression, which is often enough to enable the participant to demonstrate confidence and their skills may be perfectly sufficient. They need to be careful though and understand the limitations of their style, as they simply won’t have been taught how to quickly win against someone with a more practical style.