Co-ed teams should be aloud because, personally girls would learn more if they play with more advanced players which in this case would be guys. Some girls are built for guys sports teams like football, soccer, volleyball, dodge ball, etc.
They can be allowed but only if people choose to be put on a co-ed team and not forcefully put there. One major problem with this is that religions in the Middle East like Islam don't allow males and females to play sports together. But as technology increases things do change and people are starting to forget their old ways.
According to Dorothy L. Schmalz, a professor at Clemson University and Deborah L. Kerstetter, a professor at Pennsylvania State University, "From an early age, children show signs of recognizing behavior and activities." Many of the kids on Co-ed teams use these as memories when they grow up, and immediately think that after a season of playing on a Co-ed team that is how it should always be. When in truth girls and boys should be able to play together equally. When a girl or guy joins a coed team the opposite sex would be happy and excited to go to practice.