The mistake you're making and insist on making is making it about the male-female dynamic. Two men with little in common will not be friends just because they're men. If I like strip clubs but I have a friend that doesn't, we don't go to the club together and that friend could be a man just like it could be a woman. But
if you can't be friends with a woman just because she's a woman, that's immaturity. Not being able to be friends with someone you don't have much in common with is perfectly normal.
This is where your idea lacks depth.
I said "Two mature people that are male and female will have a hard time being friends not only because of the sex thing but more importantly men and women don't share enough interests to be friends usually. And the fact that she's a man and you're a woman."
There is no just. I gave multiple reasons why men usually* cant be friends. I didn't say "men cant be friends with a woman because she's a woman".
This is also where you lack depth.
I have a three brothers and one sister. I am no more a brother to those three than I am to the one. It's the same thing in friendships. Being a woman doesn't make another woman a better friend just because she's a woman. It may seem like it and some women want to propagate that myth but it's not true.
There are ground rules (usually unspoken) to every friendship.
I don't need to understand some mythical boundary to understand my friend.
While i agree with most of what you're saying i disagree with what i put in bold up above. These boundaries dont help you to understand each other. It helps to keep the friendship intact. That's why i said "good fences make good neighbors". I never said that you need to understand the boundaries to understand her. Actually i said that having no boundaries is a good and bad thing.
Age is a better determinant of how close friends can be than sex. It's much harder to talk to your much younger same sex friend than it is an opposite sex friend closer to your age.

Hell yeah.