I don't think the reference is pointing to a general lack of ability in the young 'u s, rather a possible lack of desire to learn to shoot and hit choosing instead to carry handguns that whose capacity will allow lots ammunition expenditure.
I think it's just a tendency for old people to assume that young people are stupid and lazy.
For every young guy blazing away and not hitting anything at the range I can show you an old guy shooting slow and not hitting anything. Same problem, same result, just different methods of sucking.
I'm sure that "once upon a time" everyone was a pistolero and then Gaston came along and ruined everything......