I admit to having one. I use it to polish the insides of trigger guards mostly. A split rod holding a strip of grit cloth or paper works good. Other than that,,an occasional use with a dental drill in the chuck to undercut a wood repair for gluing or to lay in a steel reinforcement ] rod. That's about it.

I just never found the thing that overly useful for what I do.
They and cheap screwdrivers have provided me with an awful lot of repair jobs over the years though.