It has less to do with mercy and more to do with ability. Women can't compete with men at the NBA level. A woman, Ann Meyer, was drafted by an NBA team many years ago. More as a publicity stunt than anthing else.
I was thinking of her specifically when I said the NBA. I saw her work outs. The men took it down the lane and she got clobbered. Over and over again. She didn't last long at all.
At its higher levels, collegiate wrestling is a blood sport.