To sort of drive the point home.
Ultra realistic simulation-esque training has its place. Practicing the real thing like it's real is important.
But most training does not fall into this category. Usually a training exercise takes one thing and inflates it to put the trainee in an environment to learn and master one or two particular important aspects.
Take athletic training for instance.
Athletes don't train just by constantly playing match after match after match. They run drills and training exercises. A soccer player in reality will face a highly dynamic playing field that changes every second, with teammates and opponents all shifting around as the ball is constantly in motion in order to get into a goal. When in training, however, their coach may have athletes simply stand in a triangle and pass the ball back and forth while a fourth and fifth athlete try to steal the ball. Not realistic by any means. First its a static exercise: it completely ignores the fact that almost all passing is done while moving. The fact that there are only 2 defenders vs. 3 attackers is unrealistic. And it utterly ignores the fact that such a thing as scoring exists in the game. However it does allow the players to develop confident and intelligent passing and trapping skills while under mild pressure, which are crucial to successful play.
Similarly, the athletes may be subjected to repeated intense 200-meter sprints again and again and again, for an extended period of time, despite the fact that they are unlikely to do so in an actual game. The overkill of intensity ensures that they are more than sufficiently conditioned for an actual game.
Similarly a lot of military training–even the more intricate ones that more closely resemble reality–are designed in a specific way to facilitate the growth of certain skills. The difference being, however, that you're probably more likely to have a 2v3 rather than a 3v2. Achieving a simulation of the real thing isn't always the point, even in fairly realistic exercises.