I do find standard dating apps to be full of both men and women who refuse to be upfront about what they like, want and expect from sex. The more people start talking about it on profiles and in chat before actually having sex, the better imo.
I'm not putting exactly what I like on my profile, because I'd get a whole load of blokes who'd want to meet, and then complain I didn't put out, but my profile says I'm into X, and that'sthe only reasoni they matched, etc... I might be into X, but not with just anyone. I still need to find them attractive - to have that chemistry.
Also, a lot of people aren't always sure about what they like. There have been some things I liked the idea of, but when it came to the reality, it's not so good. Some things I have very strong boundaries with anyone, but there are other things that with someone I know and trust, i feel safe to do, but not with others. Some people who have been in long relationships think they're not that into sex, then a new partner makes them realise otherwise- it was about the partner more than themselves.
However, while I'd not put it on my profile, I would normally expect to have talked about it before we go to bed together, so I agree about more openness there. But still, there will be plenty of people who may not know about some things, because they've never tried. I've learnt a lot about me while dating, not just others.