Simplest explanation seems to be when there's a bunch of mating-age humans in one place, some of them mate.
You see this with educational institutions, work, sports clubs, and so on.
What I don't see is that people join the institution with that market as an intention. At least I have a lot of friends and none of them have ever said they did anything other than perhaps a dance class in order to meet someone. Longer term commitments like university often end up being where people meet a partner, but don't seem like that was part of the purpose.
You see this with educational institutions, work, sports clubs, and so on.
What I don't see is that people join the institution with that market as an intention. At least I have a lot of friends and none of them have ever said they did anything other than perhaps a dance class in order to meet someone. Longer term commitments like university often end up being where people meet a partner, but don't seem like that was part of the purpose.