I did not read the article but I do think starting young gives you an advantage - "Mental". Confidence is one of many components in the mental aspects of any game that helps the most.
But then, look at how many pool players started playing golf later in life and ended up with a single digit handicap in short time. I just think that some people are able to more readily adapt to sports than others. Being young helps but being "Sports intuitive" is best. I define sports intuitive as rapidly managing the mental aspects.