Mark Cuban's definition of superstar is that it's a player who can carry a mediocre roster to 50+ wins and a playoff win. KG won 50+ games multiple times, but kept getting knocked off in the first round. He did finally win 58 games and make the WCF, but he had some help that season.
LeBron, a true superstar, carried a team to 60+ wins with Mo Williams as his 2nd best player. That team won like 15 games when he left.
True superstars can do a lot. Superstars are very rare, though. Pierce, for instance, was never a superstar. MJ, Bird, Magic... those guys were superstars. But yeah, you can't have a complete dumpsterfire of a team around him or they'll struggle... as we saw with KG (borderline Superstar) late in his Minny tenure. Anthony Davis seems poised to take the Superstar label and his teams have been atrocious. Even Michael Jordan, the undisputed superstar of superstars, never had an above .500 record without Pippen. His team finished with losing records his first few seasons before the arrival of Scottie.
So while teams like Minny and Philly have made the first moves by acquiring players with legit superstar potential (Towns and Embiid), it remains to be seen whether the right mix of talent will be put next to them heading forward to turn the corner. I will say that looking at both of those rosters and the kind of assets they have, I'll be absolutely shocked if those teams aren't in the playoffs within the next 3 years. Barring injury, both of those teams should be cranking out 50+ wins shortly.