this a relatively recent change, 1992. from the basketball "dream team" wiki:
In 1989 FIBA modified its rules allowing professional athletes, such as NBA players, to compete internationally.[8] FIBA agreed in April 1989 to allow professionals to play in the Olympics, despite American and Russian votes against the proposal. USA Basketball asked the NBA to supply players for its 1992 roster;
if 24 years is recent. I just realized that I'm an old man now.
No. Look at any of the sports that have large followings outside the Olympics: Soccer, Basketball, Golf, Tennis, etc.