It's true that some pornstars have capitalized from it, ex: nadine jansen girls like katerina or micky bells. But some more popular ones like Lana Rhoades or Karlee Grey or Lena Theplug have been pregnant and did zero lactating content. It might just be that they're separating both things, and it's also normal that regular people would think that lactation and sexual arousal do not go together; a college professor once told me that since lactation and sex are both natural things so there shouldn't be a restriction on connecting them. Low milk supply theory is most likely, and if that's the case well guess we'll have to wait for someone who'd wanna miraculously pay $1000 dollars on her stream to watch her do it.