Several years ago I was having lunch with several people working at my company's office in San Diego. One of the people there was a former men's soccer player at University of San Diego. Somehow the discussion went to when his team scrimmaged with the USWNT (the one that won the 1999 WWC) once. He said there wasn't a real comparison. His men's college team was bigger, faster, stronger, and overall better than the best women's team in the world. It's frankly an unfair comparison.
This is the basic reason why there has always been controversy over those with male characteristics being eligible to participate as women or participate with women in some capacity. The case of Caster Semanya may be the most obvious, but there were those who tried to compete as women after sex reassignment.
However, we have a system where women are allowed to compete separately to create a more even playing field. I mentioned tennis where major prize money and sponsorships are similar. Certainly I've heard of some women's tennis players seeking out men to play against to see if they could beat them. Back when Jimmy Connors and Martina Navratilova had their "Battle of the Sexes", she was given certain advantages where she even admitted that she probably couldn't win straight up. She accepted that fact and moved on.