Beck's explanation of burnout is the most sensical I've ever heard: the runner has simply
peaked. I don't see the benefit physically of delaying the peak until the late 20s, which isn't even possible anyway.
There's little challenge in the activity of running compared to sports that require skill, gamesmanship, or leadership. In the sports with less substance the athlete has a lot less potential at 28 than 18. Weightlifting has actual skills that need to be learned and perfected over a long period. Distance running does not.
Teenage swimmers routinely win gold medals and their training is notoriously demanding but there are few telling them to hold back and peak at age 28. Training hard during the teenage years has advantages including a body that's outgrows injuries, less weight, less responsiblities, and a support system provided by the family.
Beck's ideal mentioned in the comments is a teenager who does her best, acknowledges that diminishing returns are a sign to move on to other things, and moves on to the next thing. He implies that this is what well-adjusted teenage runners do if they don't have others' expectations imposed on them and the model of peaking in 10 years.