Tinder depends on both network effects to become a market leader and overall gender asymmetry to create a network that is very valuable to those who are looking for a match. Those other examples may use network effects, but they don't exploit the overall gender asymmetry to the same extent, making the comparison between the services weak. It's fine if you disagree, but to many people, that $20/month may be worth it if it improves their odds of finding someone.