There's been a lot of talk of the decrease in 'cost' of sex, etc in this thread. I want to chip in as someone who has spent a LOT of time on tinder.
Last month, I was spending SEVERAL hours a day swiping on friends' behalf on Tinder. We'd swipe till our eyes hurt, and we'd swipe again. You get a limited number of swipes (and total 'targets') per day, so once someone ran out of their daily quota, I'd swipe for someone else.
The process is TIRING! -- looking at attractive/ people at their best putting on their best show is tiring! It's doesn't seem to be screen fatigue -- there's likely an upper boundary on how many faces/people you can process in a day. We'd end up not checking people's profiles and swipe based on the amount of skin showed on profile pictures. It sounds ridiculous, but being judgmental of people's face/facial features apparently gets tiring at some point.
This leads me to believe that the interactions don't come for free -- they may be cheap, but the costs exist.
So as someone who spent all that time on Tinder, it is not clear to me what 'friction' Tinder removes as compared to dating sites say, 10 years ago. Having a hookup app on your lap, and on your cellphone is not that different. Or sites on the desktop 15 years ago. I know people who think 'mobile' hookup apps are the most godawful things to have happened in the world (and that because, as a lot of people have said here, because they reduce the cost of interaction), but that's not significantly different from say, 10/15 years ago, is it?
If 'hookup stats' are really higher, it could be because not everyone agrees on the definition. For a lot of my friends, going over to sleep at someone's house constitutes a hookup. I'd imagine something like that would have happened 20 years ago anyway in an offline setting, but you'd have met the person in a bar, or a club or what have you. That you happened to have met them on Tinder doesn't make it an 'apocalypse' for the dating type.
All the friends I swiped for ended up going on multiple dates, some in the same week. Two ended in a committed relationship, and one who never wanted to be in a relationship was almost dragged into one. I mention this because without tinder, he would never have been out their anyway. So here's my theory: tinder is bringing out all the 'marginals' -- people on the relationship margin who would otherwise not have been 'out there' anyway. Since their ratio to the general population has increased because of increased visibility, it seems that more people are NOT into dating. That's a fallacy because it does not control for the marginals: they'd not be 'relationship minded' without tinder anyway.