the superhero pattern is a problem for teams
Firstly, as mentioned above, the definition of superhero used in this study just captured the core team. Having a core team isn't inherently a problem.
The second problem is that this is a study of open source development. When people are being paid to develop there is a completely different dynamic to a project where contributors choose to contribute.
The superhero pattern is a problem in a work environment where a group of developers are trying to work as a team and one team member, often cto or "lead developer", doesn't work with the team and instead pushes their work on to the team as the team are trying to focus on their own work.
This behaviour often plays out to the hero's advantage. A team nearly completes a feature, the hero pushes a super new widget that performs ten times faster but breaks the teams feature. The customer sees a performance improvement from the hero and a failed delivery from the team. Bad managers facilitate this behaviour by not calling out the hero for breaking the feature.
By all means be a hero on your hobby projects. When you come to work on a team then you need to focus primarily on working in a team, all your clever code means nothing if you're just screwng up every body else's work.