That is something that they will have to answer themselves. Obviously they were just people accessing the internet by a convenient and available means and never considered that it would be a problem. It came up not because of any real sockpuppet concern but because, IMO, a pair of POV-pushers used checkuser to attack their "enemies". The POV-pushers even tried to checkuser me and another completely uninvolved editor, Lsi John, before their fishing expedition was sent packing.