I wondered the same when I read that earlier today too.
If it's a reality, I'm thinking less stories will actually be published around here My story is my own creation and property and if I'd thought for one second that posting it here released all my rights to it, I wouldn't have contributed.
As pointed out, I'm assuming that this new rule is only from the here on out and not inclusive of what's already been posted and submitted.
The sad fact is, that is the same thing which was stated years ago... and the floodgates of stories have not closed. Although some really good writers no longer post here for just that particular reason. To the detriment of the site's overall quality, I'm afraid.