I base my comments on shooting handguns for over 25 years, and teaching IDPA shooters for 10. I see new shooters come to the sport who have been so brainwashed that anything smaller then a 40 is a "girl gun" but they can't shoot the one they have in less the 9" patterns, then blame it on the gun.
Yes, the bigger guns amplify the flaws but they also make it harder to see them in the first place. I am an excellent shot. On a good day I can hold 2" or a bit less at 25 yards with either my left or right hand in slow fire. I can usually do the same right handed double action with a revolver. (can't do it left handed yet) Inside 20 i expect rapid fire strings to group inside 4". There are faster shooters, and more accurate ones, but i haven't met any in a bit. So my opinions are based on my teaching experience, abilities, and two decades of trying to get better. Yes, you can focus on the basics and get better over time, but you will do it in less then a quarter of the time with a 22. If you HAVE to have a center fire, a 38 with super light target loads is an ok second option. I suppose you could do the same with a 9 or 45 if you drop in lighter springs....but all at much more cost, and no improvement to the learning experience.
It sounds like you are a shooter who's actively working to get better! And i salute you for that. To many seem to come to the range just to make noise. And if they're having fun and being safe, have at it. It's a free country. But there is a reason you will always here "make the first gun a 22". If you use it as a learning tool you will progress much faster.
I've lost count of the number of times that I've been teaching a shooter, and had them frustrated with random shots. You tell em their flinching and the good ones listen, but even then they struggle to stop, because they can't see what their doing. Some times slipping a snap cap into the magazine mixed with live rounds it enough to show them, but they i put them behind a 22 for a few magazines and the lights come on....OH! that's what i'm doing...I can see it now. No guess work. I have a brand new shooter who's groups went from 7-8" to less the 3" at 7 m in 30 minutes, after he'd been trying by himself for more then 2 hours...because all of a sudden he could see what was happening.
An I will disagree. It ISN'T about recoil. I shoot a 22 the same way i shoot a 44 mag. Yes you will see more of the error with the mag...but you will still see the error. and for about 4 cents a shot, as opposed to 2 bucks. And with less cost you can shoot more, and with less recoil/blast, you can do it without getting tired and making mistakes. Practice doesn't make perfect. Perfect practice makes perfect.
No, the calibers are not exclusive. And yes, a bigger gun is fun...hell, my handgun stable is running about 80 or so units at present...i value diversity

But you will never go wrong with a quality 22, and they can be had so cheap (350 give or take a bit for a buck mark) it's false economy not to have one.
Shoot on, have fun. Great discussion btw, thanks for taking the time to reply.