has it right I think... and I'd opine that there's nothing inherently wrong about the .22 Magnum cartridge...for its intended use, as I understand it, as a rifle based varmint round for those that couldn't afford the bigger center fire cartridges and liked the idea of a rim fire...i.e. less noise in populated areas and good workable accuracy out to 125 yds for wood chucks, crows, ground squirrels etc., and cheaper than the center fires.
Ruger came out with the Single-Six in a switch cylinder gun that appealed to many, myself included, and I bought one for my wife in early '73. It's been used to teach a lot of new shooters over the years, but in all honesty, we've used the .22 Magnum cylinder maybe a dozen times. It just didn't make sense in a revolver...our use being cheap single-action practice in an accurate gun. The gun is a joy to use...once it's out of the holster...but that big, undercut hawk's bill front sight snags a lot of leather duff on the way out!
The magnum, at considerably more expense, did not fill that 'cheap practice' niche, and too, the muzzle blast wasn't appealing. Our 5-1/2" barreled gun is very accurate with the .22 lr cylinder in place...good groups (see pic below) at 25 yds with selected ammunition are easy from a rested position...but the .22 Magnum is not that good...more like 2+" at the same distance. As a hunting round, for varmints up close, it would work out, but for squirrels, rabbits etc., I'd say it was excessive unless head shots were made...difficult for all but an expert with any handgun.
So...from my viewpoint, it's a 100+ yd small varmint round when housed in a suitable rifle, but fills no discernible need in a handgun.
Best Regards, Rod