I don't think it's zero sum. Not everyone is into the same parameters. Or at least we don't weigh them the same. Supposing I don't know anything about women, I would at least venture to say that nerd guys like myself value intelligence in women more than the average person.

But even supposing it was zero sum, and supposing I'm a "low value" male and I deserve a "low value" female. The dating sites could fail to show us to each other, leaving a lot of people single or dissatisfied because they matched too low.