There are really only a few teams that have won championships. Most teams do not get that one superstar or just that right mix of players and coaching.
Shaq, Kobe, Duncan, Jordan, Magic, Isiah Thomas, LeBron, Bird.
Those players account for all of the NBA Championships of the last 30 years (save 3). This was by design. The NBA rules were designed to highlight individual talent and one-on-one play and raise the impact of superstar players. It seems even the refs added to that. If I were not historically addicted to the Suns, I would not even watch the NBA. While not technically, it is a fixed league. It is designed to give players like LeBron an advantage and make everyone else one form or another of the Washington Generals.
They have made some attempts to change it in recent years. Allowing zone defenses is a help. Strangely, LeBron's move back to Cleveland seems to have thrown a wrench in the superstar team thing. This year might be wide open.
End of rant.