While Murray and Parros aren't the only problems facing the Habs, they're important for two reasons:
1- depth players do matter. If the bottom of opposing lineups is crushing yours, that's not any better than if the top of their lineup was crushing yours. You just end up being beat by third-liners. And when guys like Murray start in the offensive zone and end up being hemmed in in the defensive zone, it makes life harder for everyone else, too, even once he comes off the ice.
2- they're symptoms of the root problem: the organization's philosophy of team-building and hockey systems is broken. Murray is the rattling noise in the engine that tells you you have a crack in the engine block.
You'd be hard pressed to find a team or fans who don't think their #6dman or 13th forward aren't horrible and liabilities on the ice.
You can choose to focus and over analyze a common problem amongst ALL NHL which is, poor #6dmen and/or #13th forwards. It's easy to complain about Murray and Parros, it's the 'low-hanging fruit'. I get it...
I guess it helps gloss over the real problems on this team...