First, thanks for your post. All good points.
As far as BB goes, you start out much, much closer to making that tournament than anyone in the USA. That is my point. It would take me five seasons if I went on an unprecedented run to win the NBA in my fifth season of unrelenting success. No real chance of that. I do think, however, that I could win the national championship in a small country in five seasons and be in BBB. Perhaps I'd get smashed, perhaps I'd win a few. I don't know. I do know you have a much better chance of getting there sooner than I do.
All the world playing in one pyramid is MUCH closer to reality than the current BB system. Reality is the NBA on top and USA college ball (allegedly amateur status) second, with other World Leagues hoping to get third and fourth tier American players so they can dominate in their local systems. I'll allow the class of basketball played around the world is improving, but the USA just easily won the world title without even fielding its best players.
World-wide basketball is exclusively the province of National Teams.
Having everyone start out the bottom in multi-national leagues allows for equal opportunity and equal struggle.