To elaborate on this point a bit, the reason this happens is that modern television merchandising aims for total market segregation.
In a nutshell, it’s much more efficient to sell things to people if you can divide them up into tightly defined subcategories that have no interests in common; that way, you never risk accidentally competing with yourself.
This is why children’s toys (and toy sales channels) are actually much more strongly gendered these days than they were forty, thirty, even twenty years ago: one of the basic market segregation splits they’ve decided to use is “boys versus girls”.
Ever wonder why you see Avengers t-shirts that leave Black Widow out of the group shot, or Guardians of the Galaxy action figure lines with no Gamora? That’s market segregation in action.
The upshot is that shows with crossover appeal can actually be cancelled for being too popular with girls; they’re viewed as “stealing” the female market from the specifically girl-targeted media that rightfully “owns” it.
This is the sort of thing folks are talking about when they say gender roles are socially constructed, by the way. The gender split in media merchandising? It’s not just artificial, it’s deliberately imposed as a top-down marketing strategy. When folks try to justify it by saying “this is the ways it’s always been” or “this is just what the market wants”, they’re lying through their teeth - this is, in fact, the merchandisers dictating to the market what it wants in order to sell stuff more efficiently.
(Interestingly, the reverse isn’t always true: if a specifically girl-targeted show unexpectedly becomes popular with boys, sometimes rather than being cancelled, its merchandising will shift to court the male collector’s market. TV execs are so sexist, even their sexism is sexist.)
