I'm not sure what dating apps optimize for. It's easy to say "for hookups!", but it seems like a very low% of matches on those apps lead to any kind of in-person connection, date or hookup: anecdotally I think I had a few hundred matches on Tinder, but only went on ~10 dates / hookups as a consequence. For most matches, the conversation would fizzle after a few messages. Maybe it's different for straight people?
My hypothesis is there's a "Market for Lemons"[1] problem here: take a pool of potential matches on Tinder. The pools narrow like so:
100% of people are on the app (given)
x<100% of people will match with an average person (picky)
y<x% of people will message or reply to a message[2]
z<y% of people will go on a date / hookup with someone[2]
People in each pool will be selected out of the swiping pool, leaving the people left for you to swipe on being, on average, less committed to ultimately going on a date. For example: people in the `z` group will get into short/long-term relationships and stop using Tinder. People in the `y` group will be busy texting with someone they met on Tinder (using pickup lines, etc.) and swipe less. Etc, etc.
I'm not sure how a dating app would solve this issue. Traditional ways of finding partners, like meeting people at a bar or hobby group or at college, doesn't either: it's just there's a benefit to making friends or talking to people beyond trying to hook up or start dating them. Most people, if they make 5 friends at a college club but don't start dating any of them, are still happy, I would think.
[1]: https://en.wikipedia.org/wiki/The_Market_for_Lemons
[2]: Why would people match or reply to a message, but not want to go on a date? I've anecdotally known several people who do this: some just wanted validation from random strangers, some are just shy and would theoretically want to go on a date but didn't work up the courage to actually do it, etc. etc. Lots of reasons.