The problem is, overwhelmingly, that no one hikes with a gun in their hand. THAT would be a fairly effective visible deterrent.
No, they typically carry the gun in their pack, and sleep with it.
I'd venture a guess that of the women assaulted on trails, very few occurred while they were sleeping.
But if it makes them feel better and gets them out there, that's OK.
Bear spray can be carried openly in many areas without the stigma a firearm creates.
As I indicated, I think these things are for the emotional well being of the carrier, more so than the real physical.
Its similar to when a hurricane is approaching and their is a rash of preparedness actions that are of little value. When confronted with a situation in which they are powerless, people grasp at something that makes them feel as if they have SOME power over the outcome, regardless of how useless it may be. To do nothing at all creates great stress.