From Sarah Gooding on WP Tavern:
The official Facebook plugin for WordPress launched in 2012 with the help of engineers from Automattic and currently lists 14 contributing authors. The plugin is active on more than 200,000 websites, but Facebook has not updated the plugin description page to let users know that it has been abandoned.
The Facebook plugin has received no updates since March 2014, and support questions have gone unanswered for approximately a year. The plugin’s star ratings have plummeted to 2.2 out of 5.
Ugh. This is an unsurprising but huge fail by Facebook. Honestly the plugin was never great, though at least they were trying for a while. It's a bummer to see it flounder now, with nobody really seemingly willing to pick up the slack.
I completely agree with Ryan Sullivan in the Tavern comments, where he states, “the only way this would thrive outside of Facebook updating the plugin is if it’s on a premium basis (paid for plugin) due to the number of updates you would need to make on a monthly basis.”
It's too bad. Meanwhile, Facebook reported over $3.5 billion in revenue in the first quarter of this year. They probably just can't afford to support this plugin.