I'm forced to wonder how much of this is studios and executive producers imposing lesbian tropes on writers and filmmakers.

The example I know from my own community is that of the "Tranny Tropes" that get imposed every time the media cover transgender folk. For example, I know of one -- one -- news story about a trans woman that does not have a picture of her putting on makeup. Trans feminist Julia Serano tells of social justice activists who were cut from news stories because they refused to pose for putting-on-makeup pictures.

I imagine the pressures on lesbian storytellers are just the same.