There are other reasons. Here's the big one.
The price of 5.56,9mm,45acp etc. has caused GUN manufacturers to produce a large array of new .22 versions of their larger caliber firearms. They did this to fill the demand for firearms that are affordable for training and recreational shooting. Now suddenly the number of shooters wanting .22 ammo to feed these new guns had risen dramatically. So the reality is .22 ammo is wiped out everywhere because of the price of larger caliber ammunition.
The irony was these manufacturers that are producing .22LR variants of higher caliber guns were made specifically for the purpose of being able to use the guns you are familiar with, but with the affordability of a lower caliber .22LR round. Well, we all know the availability of .22LR is nil and affordability is relative but not what it once was. Hell, I have a S&W M&P 22 that I have never used based on the scarcity of .22LR and the only reason I bought it was the perceived bang for buck over using 9mm at the range.