A soft focus filter on the camera will soft focus everything and there's no hope of recovering sharp edges that you may want.
At least with Photoshop or other software tools, you have the option of having all in soft focus, portions in soft focus, and can adjust as you go.
I did get a kick out of the comment about age creating sufficient soft focus... as I sit here with contact lenses in and reading glasses on. I guess that makes me "ol' six eyes"