Um he did have people behind him....Manu, Toney, Horrey, Bruce Bowen, Come one...at least 3 of these guys will go to the Hall of Fame.
Duncan never had a Shaq, a Wade, a Gasol/Bynum/Odom/Artest, etc...
Robinson was stillgood in '99 but there was no other notable players on that team, and in '03 Robinson was at the end of his career averaging 8 ppg, Duncan led the team in every statistical category that year and layed waste to the 3-time champion Shaq-Kobe Lakers, the otehr guys were brilliant in their roles but were never superstars in their own right. hell other than Duncan the spurs have only had maybe 2-3 all-star selections his whole career.
put gasol/bynum/odom around Duncan and he would have won 7-8 straight titles.