They are except for when they aren’t. There are chromosomal arrangements other than XX and XY, and there are people who don’t have the physical attributes you would associate with their chromosomal category. Defining them as “male” or “female” because of their chromosomes is essentially begging the question; we have…

Well “man” and “woman” are socially derived ideas, but “male” and “female” are decided by chromisomes, arent they?

If we are going to hold two separate events for men and women, then we have to have some distinct dividing line between who is “a man” and who is “a woman.” It may not be fair to everyone, but you do have to draw a line somewhere.