I had a paper route when I was 12.
The work itself wasn't important but learning responsibility and the value of money was important.
It was the first time I did anything completely on my own without being directed in some way by a parent, teacher, coach, etc. Without that job and after-school/summer jobs I had when I was older there is a good chance I would have made poor financial decisions in early adulthood.
With 18 year-olds getting credit cards shoved in their face the day they show up for orientation, after probably signing up for student loans, it's probably a good idea for them to have earned money on their own for a while.
Right?
Learning things a little at a time, when the stakes are low/non-existent is the way to go. From early teens to partway through college when you get an off campus apartment you can learn how to apply for a job, how to interview, responsibility, managing your money, responsible credit use, professionalism, bill paying. All this over the course of years, with a support system when you make mistakes (hopefully).
I guess some people think you should just have all that dropped on you like a ton of bricks the day after you get a diploma.