Yeah, I've never really gotten this. Companies have this impulse to treat social media pages as expedited call centers. That's bad for everyone; it's annoying to have to air your problem publicly and deal with a social media manager, and it reflects badly on brands to see complaint after complaint. This behavior only could've emerged because they indulged it. I'm not sure what PR training course advised doing this instead of sending a message that support requests go through channel X and then deleting the complaint/message/request.