I found one article about early specialization in sports that summarizes the causes: [text in brackets are my comments]
"ROOTS OF [early] SPECIALIZATION
Perceptions of the East [Americans notice that Eastern Europe sports programs start young]
Getting Ahead [Parents want an edge in sports results, in school admissions, in economic benefits]
Labeling [Kids get labeled as talented]
Pursuit of Scholarships [Families chase scholarships, despite low odds]
Pursuit of Professional Contracts [A very small but visible percentage go from high school to pros]
Sporting Goods Industry [The training/industrial complex advertises]
Expertise Research ['deliberate practice', '10,000 hours', …] "
(from:
http://nyshsi.org/wp-content/upload..._Youth_Sports_in_Society-Malina-CSMR-2010.pdf )
BTW, it's not that I had never heard about early specialization before Foley mentioned it. It's just that I can never remember the reasons I read for why it's happening NOW and not before. I suppose the culture is simply evolving due to, I'm guessing, economic anxiety, college-admissions anxiety, greater resources and attention to parenting, greater media exposure of what can be done and what others are doing, and ???