No, Boys and girls should not play on the same team I do however believe that for every male sport there should be a female counterpart. The sports between men and women are separated for a reason if boys and girls played together no one would be able to play at their best. You have the problem of sexual harassment on the field the girls could be hazed or there could be a hesitation due to feelings for one another. If you have boys and girls on the same team then personal relationships would no doubt get in the way of the performance. For example if a man and woman were playing soccer in their team and this particular man and woman were in a relationship when it comes time to pass the ball and the girlfriend wants the ball or vice versa I can guarantee that the man or woman will pass to the latter on a bias judgement.
True, feelings might get in the way. Girls and boys also have different strengths, but those strengths could be a great benefit. I know some girls don't really care, but the ones that do won't let anything get in the way. I am on a swim team with girls and boys, in fact, if I do have feelings it makes me work harder so I can look better. :) Some girls, might let feelings come between them, but that is natural.
Sexual harassment can happen anywhere, like school, but does that mean boys and girls shouldn't learn in the same school? No!
You don't understand swimming is a mixed sport because lack of contact. You are in your own lane doing your own race and you do not have to worry about the competition. During sports like swimming, skateboarding, skiing, snowboarding contact with the opposite sex is unnecessary so therefore mixing them will do no harm. But sports like football, basketball, soccer, boxing, ufc, and baseball are all contact sports where contact is unavoidable so they need to stay separate. I hate to sound all sexist but the way the world is and works men are naturally stronger and sturdier than women. Men develop muscle naturally and in order for a woman to become a body builder she needs to take heavy hormonal pills and take steroids every so often.