All this makes one fatal assumption, and that is players are destined to become what they become, regardless of cir stances. But there is very much a case to be made that Kawhi becomes Kawhi in large part because he was drafted by the Spurs. Likewise with Giannis. Yes, in hindsight, Giannis should have gone number 1 - but if he does, then maybe he's out of the league just like Anthony Bennett as this point.
The random Tankathon mock I just ran has Dariq Whitehead going 25 to Memphis. If Dariq Whitehead becomes an all-star in 3 years and Amen Thompson gets picked by the Rockets and doesn't, it will be easy to look at that and say the Rockets should have taken Whitehead at 3 instead of Thompson. But that ignores that Whitehead becoming what he did may have heavily relied upon the fact he was playing off of Ja instead of learning to be an undisciplined chucker in Houston. So Houston takes Whitehead #3, gets absolutely hammered in the press and by fans, then Whitehead doesn't become an all-star, because the Rockets continue to suck, and the GM gets ceremoniously fired.
It's not as simple as just "take the guy you think is best whenever your pick comes up"