In this the company fills jobs with keen but cheap young people to save money. These people work hard, get experience and take qualifications. Three years later you have a cohort of young people with excellent CVs and qualifications above their peers... that the company can't afford to pay the market rate for! Then it loses a whole cohort of great staff.
That is a self-fulfilling prophecy though. Why do they churn, because they are young, or because you refuse to pay them the same for doing the same work as their peers?
In this the company fills jobs with keen but cheap young people to save money. These people work hard, get experience and take qualifications. Three years later you have a cohort of young people with excellent CVs and qualifications above their peers... that the company can't afford to pay the market rate for! Then it loses a whole cohort of great staff.