To have an application autopost to Facebook requires that you give Facebook access to your web site and allow their "engineer" to log in and test your app. These are, without exception, clueless and underpaid non-technical people in third-world countries.
I've gotten all of my applications approved after much angst.
What I didn't do was turn off Facebook's access after. Now they are asking that access stay open and they pop in every month or so and post a test.
I'm beside myself with distain.
With billions of users, Facebook owns this market. There won't be a "MySpace Event" that unseats Facebook. Ever. The only way they'll lose their dominance is if we get decentralized social feeds, much like we have a decentralized web of HTML sites.
We need a social protocol like HTML and browsers that support it.
We then need unassailable identity verification (or proper anonymity) and a protocol for creating a social graph (think "your friends" or "your followers" and such).
At that point, Facebook, Instagram, Twitter, TikTok, et. al. become obsolete and the users take back their content and control.
It'll be another 3-5 years.