If you have to practice with your carry gun, using the same ammunition you use for self-defense, why is it okay to practice with other guns? Why is it okay to practice with a .22?
There are some fundamentals to pistol shooting that are not specific to a given pistol or caliber. There will still be some gains in practicing other pistols or calibers. Some skills are perishable and some bad habits come back.
Flinching / anticipation (for those more sensitive to certain words) - is a healthy reflex in any other context. Big explosion coming? Normally yes: brace yourself, close your eyes to prevent debris from getting in your eyeball. Not so good in pistol shooting. You need your eyes focused on the front sight or target depending on who you ask and what technique you are using. You need follow through which is also not natural.
Trigger control despite explosions. Consistent grip that applies consistent muscle contraction despite explosions. Good stance, good posture, training the eyes to pick up the sights despite explosions.
Switching to a 22 can somewhat isolate those things so you can build fundamentals with less distraction. Then applying those to a given centerfire is easier. Asking someone to learn to shoot on something that is perceived to be unpleasant probably make them quit early on.
It's like cross training in sports. Can learning to master one sport be beneficial to other sports? To a certain degree yes. You won't have the specific skills / technique, but conditioning, agility, balance, coordination, mindset, would benefit. Probably won't find the captain of the basketball team being picked last when it's time to make teams for dodgeball.