Yeah, but that was actually Sony's call. They were the ones who decided not to allow porn on Beta. Realistically, they couldn't have stopped a filmmaker who was determined to release in their format, but it was easy enough for the porn stars to go where they were wanted instead. In the end, it was still an issue of Sony wanting Betamax to be the quality, high-brow brand.
And that's why Sony Blu-Ray
does offer plenty of porn.