> Dating apps strike me as a very low-quality (low fidelity?) way to match couples.

It's true, but a lot of people don't have the opportunity or patience for those other approaches. If they're not just homebody introverts in the first place, they may already have a pretty saturated schedule/network without many suitable people around to pair off with. This happens to a lot of people as college recedes and life establishes a professional, mid-life rhythm.

Dating apps are garbage, but alternatives aren't always practical.