Why is that?
Good luck by the way...
Ive got a few reasons just off the top of my head
1.) time for kids to mature, be ready for the money that is about to be given to them and (I'd say in all cases no matter your draft number) the fame that is going to be given to them
2.) it protects teams somewhat, for every KG and lebron theres a Kwame Brown lurking
3.) Theres a reason the NFL doesnt allow straight out of highschool kids into the league, theyre not physically ready for the game and in a lot of case not ready for the mental load that comes with schemes & playbooks.
I'm going to be speaking on sports in general, mostly the NBA & NFL ( baseball is weird to me with how they draft kids straight outta hs but they dont see playing time for 5 years)