This thread is overcomplicating things.

The male and female sex drive is different. Men are much more drawn to visual stimuli for arousal. This is why porn is so much more effective on and commonly consumed by men. The amount of women who seek out porn for arousal is just a lot lower on average.

That also means that the vast majority of people who would seek out male guro would have to be gay men and you get left with very little male guro...because the vast majority of men are not gay. A wide demand just isn't really there. This applies to all porn in general, not just guro, but there are at least enough gay men(and some women) to support a normal gay industry, not so much a niche community like male guro.