Barrel lapping is one of the many faddish improvements made by Ruger owners in particular to tune their "unsatisfactory" handguns. I say "unsatisfactory" because when you read accounts of the tuning process they usually started out with a pretty good gun in the first place. There's a minor industry around firelapping, forcing cone modification, part replacement, and for all I know tea-leaf reading, that forms a system of aftermarket enhancements.
This is not a dig against Ruger, which makes good guns. There's just something about decent affordable equipment that makes people want to modify it, thus spending enough money to have bought premium equipment in the first place. Human nature, I suppose.