Leap members use their true identities, so when someone new joins I make sure they are a real person. I chose Facebook auth to get started, but I'm planning to add additional auth mechanisms down the road.

What problem are they trying to solve that can't be solved by a closed Facebook group? Do we really need another social network?

Perhaps because Facebook provides an easy and fairly reliable way to determine someone's sex. Many projects including dating sites have relied on it to do authentication for this reason.

And it’s awful. This trend needs to stop. Facebook is an ad tracking platform, not a universal authentication scheme.

I fail to see how it'd be good for this use - do they require a number of friends or something? I have 4 Facebook accounts for faking out exactly this kind of stuff, but none with any real information.

Presumably most people are not like you and have only one account. The site can make sure you have had an account for at least a year and your sex is female. Otherwise you may want to fake it to get in.

It's the most reliable "easy" way I know to determine this info. I remember an app called Lulu which did the same.

A sizeable and growing portion of the population refuses to have any dealing with this shady corporation. Facebook is not a universal authentication platform and never will be.

There isn't a universal authentication platform. Facebook is closer than most. And Facebook is strong for this in the interest of getting something out the door, to be improved later.