People love how Facebook lets them comment on and share other people’s posts. But the idea of sharing on social media has got drug companies scared. When Facebook told drugmakers that they had to start allowing comments on their Facebook pages, some of those pages started disappearing.

“Take On Depression” suddenly disappeared. “ADHD Moms” vanished, too. So did “Epilepsy Advocate.” In the past, drug companies had been reluctant to create Facebook pages without a guarantee that they’d be closed to public comments — a unique accommodation on Facebook’s part. But that accommodation ended last week.