Why gay dating sites are full sex only?

I'm not being judgemental or anything. I just wonder why does it look like everyone around you is only there for sex on gay "dating" sites like Grindr unlike other straight ones. I have seen apps such as (on my females account) Tinder is are mostly for straight relationships and it's where you almost never see straight guys sending nudes or asking for sex and never see things like "looking for fun" on their bio. What do you think is the difference?