with team = true what is the meaning of making role with team_id null

[Toylycker]

// with null team_id it creates a global role; global roles can be assigned to any team and they are unique
Role::create(['name' => 'writer', 'team_id' => null]);

what does this mean in documentation?
as long as i understand you cant assign 1 role to many teams. there is even no code that would show assigning a role to team. you can only create role with team_id and again what does making it null gives? in my case, i cant assign a role with team_id null to any user.

[parallels999]

you can only create role with team_id and again what does making it null gives?

• Recommendations for apps with a large # of user-controlled roles #2444