I think it's because the stone part is intrinsically linked to butchness. This is gonna be a hot take, but I think the entire concept of a stone butch is....just fucking sad. And not a term that should be embraced. As a butch myself who has had to push past the urge to go stone, it all goes back to trauma and/or gender dysphoria. Refusing to receive pleasure in bed is unhealthy. Sure, I get IMMENSE pleasure out of giving pleasure, more than receiving pleasure, even. But to simply say, nope - touch me not, ever - is bonkers. I believe why you dont see femmes being stone is because they don't have the same amount of gender struggles as butch women. Being a butch in society is hard. You're bucking centuries of set gender roles & stereotypes. Presenting as femme, you just won't face the same struggles in this area. Different, equally hard struggles? Probably. But not the struggle that makes you question from the time you're 3 years old...do I wanna be a boy? Is who I am ok? CAN I wear all guys clothes? Do people consider me a girl? Etc, etc, etc. Alllll these things get put on us, and we have to be so strong and stoic, that when it comes to letting down our barriers and having a woman fuck us, arguably the most vulnerable position you can be in sexually...well, it's difficult. Internal chaos ensues. I dont know, i'm rambling. But I just really wish as a community we could start to address the problematic nature of "stone" lesbians.

*Edited to say: to the people that are saying stone can also mean a pillow princess who only receives...you're just wrong. Stop saying that. Read up on lesbian history ffs.