Perhaps if you have little experience of watching boys and girls play sport together and separately, you might not realise how different a picture each scenario looks.
I agree boys’ attitudes and conduct in sport needs challenging and changing, also to benefit other boys who do not act in the manner that has become acceptable in male sports. But such changes could and should be tackled within single-sex activity.
If you have daughters and you are keen for them to participate in sports, you go through many years viewing the system through a filter of girls’ experiences and it is dispiriting having to keep fighting to keep your DDs and their friends playing sports long into their teens. There are many issues, but one of them is that not enough girls start off playing sports, and girls’ early experience of mixed PE/sports puts them off.
Once in Secondary school, if you have DDs that you manage to keep playing a sport in or out of school, watching their games is an uplifting experience. They support each other, compliment each other (even their off-pitch enemies) engage with each other, comfort each other, swear rarely, lose graciously and display a strength and confidence in their bodies that you don’t see when they are surrounded by boys. Why not let the younger girls also have that all-female experience and let more of them learn to love playing a sport (not just those who have doggedly determined parents!)
I think much needs to change in primary school PE and since the addition of the sports premium there are examples of fantastic schools being innovative and engaging all of their children to help them become interested in physical activity. My DDs primary school was not one of those and instead gave control of PE to a boorish male sports coach educated to further education level, who favoured the already sporty and did very little for the keen but less able children of both sexes. However, for my keen but less able DD2, it was the sporty boys’ negative influence that did more damage than the sporty girls.