Is that culture of injury actually normal? I went to a smaller but not tiny high school (~1000) and crutches were always notable, not a common thing for athletes.
I guess it is normal in that the people (especially the youngsters) who run or practice other sports have a much higher injury rate than people who just walk or basically do nothing.
Also, in my experience, a vast majority of pupils and students who were injured did it during a sport activity and not because of other kinds of accidents.
Maybe that coach had some bad ideas.