It's less team "Leader" so much as team "Representative" of to whom I get to burden with the responsibility of handling the conduct and activities of their team members. So if say Azalea starts getting too touchy-feely with Tarkus and he ends up in a fetal position on the Sky docks cause Azalea stuck her thumb up Tarkus's butt, it's up to Oroku to reprimand her if Beacon doesn't for some reason or another. Or when deciding what sort of missions certain team members or the team as a whole gets; Victoria would have to head on over to the Team Leader Meeting and get jobs for her and her team in order to gain some acclaim for her group and rise up in the ranks of the school, else what they would come under fire for being inactive. 

So yeah, it is a mantle of leadership. And it's going to stick, cause now you need to learn not only how to survive in this world, but how to make sure your team survives with you.