Good for her, it was a fantastic achievement. But would people have been so supportive after the fact had she been lost at sea, or kidnapped by pirates etc?
No-one would object if a 25 year old person tried to do this, but no sane person would permit a 2 year old to do this. So somewhere between a line must be drawn. And thats the sticking point, because the line cannot be fixed. I know some 16 year olds that I wouldn't trust to circumnavigate a trip to the corner shop for a tin of beans, let alone the globe.