I never wanted to combine play my Lego dudes with my sister’s Polly Pockets when we were young. Worse, combine play between my Lego dudes and Barbie dolls.
Let me now try to articulate my thoughts on behalf of the young I:
It was not about it being girlish to play with my sister. I made pizzas out of socks together with her. My most important concern in the above was the realism of the play. A person does not differ from another in such proportions as that between my Lego dudes and her Polly Pockets. I will only accept one dimension as the frame of reference. So, she can go play hers and I, mine.