Why we can't just build a better dating "market"

In short: Because as soon as one's focused on getting, which is the exact reason one would enter a dating "market" space in the first place, one tends also to notice and emphasize not having. Then one feels bad about that, and in your misery one forgets in many ways to care about other people, which makes one unattractive to those same others. And this logic applies to almost everyone participating in the dating market. Everyone is miserable about not having, and nobody is sexy.