Isn't +/- also dependent on how good your backup is, and what kind of opponents you have? How is it useful when you have so many stuff to consider and take note of?
Raw +/- isn't dependent on backups, except maybe indirectly (if the backup sucks, he has to play more of the minutes against the tougher lineups). By useful I mean "not useless." It tells you something, but one shouldn't look at it at the exclusion of all other factors. Suppose there is as player who plays half of his team's minutes, and he has by far the best +/- on his team. Suppose, by the fantasy stats, he rates very poorly. If I never saw the team play, and I look at that information, I'll think to myself, "Wow, this guy doesn't appear to do much based on the boxscore. But he must be doing something really well because he's getting significant minutes, and his team plays great with him on the floor. I think I need to pay closer attention to him. This could be a player who is undervalued by other teams." It's useful in that way.
I'd love to see a player that played half the minutes on a team, didn't have impressive stats, and yet still led his team in +/-
