What you are missing is that boys and men need to gang. With females in the mix the strengthening of character of the individual through the challenging and support of one another does not occur. If you are not male or have not been part of a purposeful four to eight man team, then you have no idea of the dynamics that are involved. Provide a positive gang environment such as BSA or leave them to their own demise such as MS13. We have enough co-ed groups. Our failing school system squeezes boys through girl extrusions and expects them to be gentlemen at the other end. Do you really want men who wear pussy hats? No. The BSA movement was based on raising men from boys. The new slant on the scouting program will dilute the institution, cause its downfall, and open up the gates of unstructured hell of boy gravitation toward thuggery.
The fact that girls are permitted does not preclude the need for boys to gang. The same is true of girls.
When we think of patrols or cooking groups, it seems likely that they might be gender segregated simply because that is what the kids want.
In Scout units where girls 14 and older are permitted, there are many years ( at least 35) and lots and lots of very positive experience. There never have been a lot of girls, but there are many that desire participating in the rigorous scouting outdoor, advancement and leadership experience. That experience includes backpacking on a 70 mile trek at Philmont or sailing th Bhamas from Seabase.
I argue that you are simply wrong.