RJB: I'm not sure where you got your info, but the diver in question was diving with buddies he knew well. I am intimately aware of the circumstances of this incident, but in deference to the parties involved, it is not my place to discuss the specifics. Only know there was a medical problem involved and buddy or no buddy the outcome would have been the same. I can tell you that the grief associated with losing a dive buddy is something I pray I never have to experience.
I have been diving since the late 70's, including a stint as a public service diver (police). Never in that time has a buddy had to "save my bacon". There was only one occasion where I made an air sharing ascent during a free flow. I could have made an ascent alone, but it was safer and more comfortable to make it with my buddy. As an instructor I teach the buddy system as one of the golden rules of diving. But I also stress the need to be your own best buddy! Proper training, careful dive planning, good equipment, situational and self awareness are the bacon savers of a good diver.