We had an amazing internal 'social media' site at VMware that was basically used like an old-school forum (Socialcast), but then the legal department nuked everything older than ~1 year old, obliterating a huge and beneficial source of org knowledge and more or less ruining the use case (you usually could find an answer for anything you needed, or figure out who to talk to about it if not).

VMware acquired the software company that created the software, failed to market it, and it's only extant as a shadow of itself internally.