I don't understand the habit of dismissing any questioning of an alleged success as "jealousy". It happens most commonly when people discuss whether someone earned their wealth - there's always someone who crawls out of the woodwork with the ad hominem "you're just jealous!" as if this even addresses the argument. I've had my fair 15 minuteses of fame for my successes as a younger lad, and now I look back and think I was an immodest, arrogant irritant. Anyway, end of prologue.
The issue here is that this article celebrates mediocrity. The world already has a low enough expectation of the mind of the child, and when it sets the bar so cheap for other children, those who were genuinely doing brilliantly are discouraged, while those hitherto lackadaisical will only remain so. I know I'd have done better as a boy if I hadn't been told I was doing brilliantly at something when, in fact, I wasn't. It is too easy to impress the average. See also: the UK secondary school exam system, etc.