Correct, not all young people speak with vocal fry, but it is more common among young people than old. So if someone is complaining about vocal fry specifically

Correct, not all young people speak with vocal fry, but it is more common among young people than old. So if someone is complaining about vocal fry specifically, they're basically complaining about young voices. All voice is learned, so I don't see how that distinguishes it from any other vocal phenomenon. We don't talk the same way as people did in, say, the 40s. That's learned.