I can't think of any downsides to going with another person.

With all things being equal, you each carry your own gear. You may share food/cooking/cleaning.

I fall and break my leg, otherwise ok - Partner calls for help, makes camp, we wait.
I fall and have some sort of head injury, but am ambulatory - Partner calls for help and shelters me, worst case guides me out.
I fall and am unconcious, not able to move. Partner secures the area, calls for help - and in worst case scenario, shelters me and beats feet for help.

If I'm alone in first case, possible second, I call for help and wait, alone. In third case, I'm hosed - the chipmunks devour me and I am never heard from again until some hunters stumble across some bones 10 years later.

I will go on short hikes, in the local area, solo, but nothing overnight.