If putting NBA Stars together will win championships how did Allen Iverson and Carmelo Anthony get swept?

Iverson and Melo were together in Denver in 2007-2008 both being superstars and Iverson was top 10 in scoring that year and led the league in scoring 4 times before and a former MVP combined with carmelo anthony a top 10 player in his prime. How did they get swept by the Lakers if people think that putting all-stars together can win championships and Iverson never won a title because he never had a good #2 scorer on his team?