Just this. Modern sporting teams rely on stars to draw in viewers, and create a relationship between the fans and the players, not just the fans and the brand.
People who don't go to see the Lakers may go to see "superman" in action, and this is same with eSports. Without a standout career, it's harder to create emotional investment in the team, and it's much harder to cheer for a player that has played for a year, and will be gone in 2.
It's one of the reasons why people in the west find Asian teams less compelling. The language barrier and lack of familiarity with the players prevents the team from creating the marketable narrative that we see in traditional sporting events.