It creates situations where some young person may not be "allowed to succeed" due to their unconventional approach and this continues until they turn a certain age by which point those in power think "This person cannot be good because they're 45 and I never heard of them." The suppression becomes self-fulfilling because they were unconventional even though their approach later proved optimal and everyone may be doing it now. Not everyone on the frontline gets recognition.
Also, because a lot of successful people achieved success by a certain age, they tend to look for and help people who are like them. Someone who is 45 and not successful has a very different worldview than someone who became successful in their first venture at 18 years old.