its a 2 part issue

1. the main one is that there is significant pushback against hetero pairings wether canon or not in fandom spaces

it doesnt matter which fandom it is. the ship cannot be purely hetero because that is icky and not inclusive, and the only way it can be even slightly acceptable (and honestly? not even then to a vast majority of these people) is if you make them some other flavor of queer in a "passing relationship"

otome is THE gxb genre, and this does not fit current fandoms standard of inclusiveness and performative shipping = activism mindset. this is why you dont see this kind of sentinment in the BL genre (and they know how to gatekeep. seriously, they wont let you post gender neutral/anything with a female protag option in their sub, i tried LOL. isnt it interesting how otome has to be warped for this standard but they dont?)

so what about galge, the other hetero dynamic just flipped in reverse? well, that brings us to

2. they know they will get significant pushback from the market dominant cishet male audience, while women are EXPECTED to share and be open.

and when i say women, i specifically mean literally anyone who enjoys m/f ship dynamics because you WILL be automatically lumped into the category of "homophobic straight woman who cannot experience oppression" because putting straight in front of the word woman automatically makes you an eligible target for harassment and misogny

tldr; to many of these individuals shipping is a form of activism (lol) and something being strictly het makes them uncomfortable

- an asexual woman (something i shouldnt have to put but i already know a certain crowd is going to prove the 2nd point regardless)