This seems like a legitimate concern. As a user, I love that the ubiquity and consistency of Discourse makes it so easy to jump in and participate in a new forum. As an admin, if I had the occasion to help with other sites I’d appreciate the consistency there as well.
(I’m thinking of all the friend & family tech support I’ve been called to do. I’m happy to help with iPhones, but I dread Android because every dang phone is different.)