>But a closer look at research on the world’s top performers, from professional athletes to Nobel laureates, shows that early specialization is the exception, not the rule.

As another commenter has pointed out, this is a more comforting and maybe also more realistic stance when it comes to professional/scientific achievement. Unfortunately, however, early specialisation is definitely the rule nowadays in professional football ("soccer"). I'm assuming it's the same for Basketball/Football/Baseball/... in the US and elsewhere.

Pretty much every player who's playing in the top leagues now grew up in an academy, where their education and social lives revolved around their football practice routine, not the other way around. That is not only the top leagues like Premier League or La Liga, but also the leagues that come below it. Players like Brinkmann, Scholl, Bernd Schneider, ... are celebrated as the exception to the rule.

I used to "play" in the fifth league in Germany (Oberliga BaWü) for 2 seasons (barely got any time on the pitch) and even there, almost every player was in some sort of specialised training since they were 5 or 6, either in the youth programmes of local clubs or private academies their parents paid a lot of money for. Everyone is dreaming of playing in the Bundesliga and the academy owners know that. Players coming from a different sport later in their childhood were the exception.