In sports, what exactly do gender divisions accomplish? Why shouldn't women simply compete with men?

The idea behind many sporting competitions is to equalize the physical attributes of the competitors as much as possible, so that skill can be the deciding factor. This is why there are weight classes in wrestling and boxing, and handicapping in horse racing and in golf. Since women are, on average, physically different from men in lots of ways that are relevant to lots of sports -- e.g, tennis, basketball, track & field events -- it has seemed reasonable to separate men and women into separate competition classes for those sports. Automobile racing doesn't implicate physical skills that vary systematically between men and women, so there are no gender divisions there. There are also some fairness considerations: using classes within sports gives more people the opportunity to play. If there were no classes, then men who currently box in lightweight divisions would nearly always lose, and sports like basketball and track & field, even at the high school level, would be virtually devoid of women....