It makes sense to me. A car traveling at 25mph but accelerating at 20mph will eventually over take a car traveling at 60mph but only accelerating at 10mph. The question's when will that occur? Depending on each person's current age and desired retirement age, they will need to choose the car that has the correct current speed and acceleration to cross a threshold at the required time. The more time you have, the more choices you have as there are multiple combinations to get you there.
Ok so it's a little more involved once you try to actually choose the stock, but I think the idea/approach is rather simple to understand. It's like you've been saying, start early and it'll be easier.
And for you engineers and math people, please ignore my simplistic and incorrect units associated with acceleration. The concept's the same even if the units are correct
