It's not for hose routing - for me, it's more for transport/handling where I think they can add value. First example, I can coil my reg hoses pretty tightly in my carry on with no fear of stressing/kinking the hose ends.
I agree that, during an actual dive, most hose protectors don't really add anything - but nor do they detract from anything. In fact the protectors on my atomic second stages keep the swivel from getting ang debris in it.
Look - I'm not advocating for folks to use them but it's not the "horror" some here seem to want to suggest claim. It literally takes seconds to slide back to inspect/ clean on my Atomic - maybe others are more difficult.
As I said, I'd bet the bigger issue with hose failures is folks never thinking about them - reagardless of use of hose protestors or not! In fact, due to my practice of moving them to rinse, I am always reminded to check my hoses before and after diving!
Dive as you see fit !