Handguns designed to powerful AND lightweight tend to be less fun to shoot. At the same time, they are generally compact enough for teaching kids and other new shooters. So combining lightweight frames like Keltec PF9 or Ruger LC9 or 9S with equally lightweight rimfire uppers from Twisted Industries works pretty well. Not much recoil, and the ammunition is still less expensive than 9mm.
As you can see from the photo, even a lightweight .22 with minimal kick is a handful for the new young marksman. A heavier pistol or in a stronger caliber would have interfered with learning the marksmanship basics more.
This approach, on the other hand, allows to work up confidence and to have fun while learning. As an adult, I shoot more with an Iver Johnson conversion kit mounted on M1911 than I do with 45ACP just because subcaliber practice is more fun.