This link is from Shin's Baldy Conditions thread on the Whitney Portal Message Board.http://www.sbsun.com/lifestyle/20170317/mt-baldy-deaths-lead-to-questions-about-trail-safety
Note the level of experience of the victims, one dead and one injured.
I have seen two YouTube videos of ascents of the Devil's Backbone in the winter where everything looked fine. Very different conditions, in one case complete coverage with good snow, the two hikers sinking in about ankle deep, wearing ski/snowboard boots and carrying skis/snowboards. In the other case, the very opposite, skimpy snow. No signs of ice axes or helmets in either case.
But who is going to tell you what awaits you up there? The story says they camped on the summit, but does not mention their ascent route, so perhaps they did not have a good idea of what they would find on the way down.