You're calling others on being new fans? Did you just look at the impressive collection of names from the '03 team, and decide it was one of the greatest of all-time?
The truth of the matter is:
Robinson was on his last legs
Bowen was a sub-par offensive player still building his reputation as the best perimeter defensive player in the game
Parker, while talented, was a 20 year old 2nd year point guard who struggled mightily at times
Ginobili, again, while talented, and an established international star, was an NBA rookie still adapting to the NBA game, and being a role player
Jackson was a minimum free agent signing, and a mostly unproven player trying to establish himself in the league
Rose, as solid as he was a both ends of the court, was a mere role player
Claxton, was an injury prone runt, who was also an unestablished player at that point
In conclusion, that team lacked a certifiable 2nd All-Star, a true star-superstar caliber creator on the perimeter, and was mostly filled with past their prime vets (Robinson, Willis, Kerr, Smith, Ferry), or talented, yet erratic young players (Parker, Ginobili, Jackson).
Just look at their playoff record of 16-8. It took Duncan putting up historical numbers (24.7 ppg, 15.4 rpg, 5.3 apg, .529 fg pct, 42.5 mpg, also accounting for 5.98 win shares, the most in a single playoff since that stat has been recorded), and one of the all-time great defenses to overcome their shortcomings.
Anyone pulling the "look at Robinson's regular season stats" argument is a damn fool. Sure, Duncan's never blocked 4.49 shots per game in a season, but guess what? No one does nowadays. Howard led the league last year at 2.92 blocks per game. The game has evolved, and become more perimeter oriented. That being said, as we've seen before, when he had to carry the team and put up monster numbers, Duncan was more than capable of doing so. If he was selfish, he easily could have had another one or two MVP's (and probably should have anyway, in addition to the multiple DPoY awards he should have won).