Here's a novel thought:
The reason most female characters can't carry their own story is because the canon they are in is usually not about them.
So of course the female character(s) of most canons can't carry her own story, because the writers of canon do not write about her as though she's a person with her own desires, thoughts, goals, and suchlike that just happen to intersect with the male character(s), but as though she's an appendage to the male character(s) - there for his convenience, use, and dismissal/destruction when his story requires it.
The reason most female characters can't carry their own story is because the canon they are in is usually not about them.
So of course the female character(s) of most canons can't carry her own story, because the writers of canon do not write about her as though she's a person with her own desires, thoughts, goals, and suchlike that just happen to intersect with the male character(s), but as though she's an appendage to the male character(s) - there for his convenience, use, and dismissal/destruction when his story requires it.