Good question. Most porn is made for men, by men, and a lot of kinks are traditionally male dominated – guys tend to get a bit more obsessed with fetishes etc and so dedicate their time and energy in creating content and tumblrs for it. Just look at the number of male chastity caption blogs, it numbers in the hundreds compared to much less for female orgasm denial.
Female denial, well let me flatter you lot a bit and say I generally find it’s the kink of the smart, discerning woman. There’s something about it, the fact it takes some self discipline, that the effects take time to develop, that it’s as much about the mind fuck as the physical effects, that is most appreciated by a woman who’s a bit more sophisticated in her sexual tastes than the average lass.
Which makes the fact it actually reduces you to a dripping horny little slut all the more exciting, that it’s almost an escape from the pressures of life into your little world of edgespace, not having having to think, not having to do anything but rub and ache and let the horniness overtake you.
So fucking hot.
It also means the captions for you lot have to be much more engaging. Making a caption for male denial is about as hard as finding a picture of a sexy woman and then sticking ‘SHE LIKES LOCKING UP UR COCK’ on it and it’ll get a bazzilion likes from wanking gents. You want seduction, mind fucks, and even then you’re scared to hit the like button (which is adorable btw).
Anyway, sorry, got distracted. 😛
tl;dr Porn is mostly male dominated, kinks for smart sexy women are niche (the best niche in the world).