Hanlon's razor, anybody? https://en.wikipedia.org/wiki/Hanlon%27s_razor . This could just be a mistake.
It looks like a mistake, FB is actively communicating it's trying to restore the content but still everyone is witch hunting.
I thought people here were more sensible to the fact that developers at all companies leave bugs/undesired behaviour behind them.
This may very well have been spec'd and developed 10 years ago, and now the reality have changed, but not the code. Because let's face it, it's not exactly an everyday use case.