If you really want an in game explanation... your the only player that matters, this is your story. Technically when your playing only 1 match is taking place at that specific time (despite the reality of thousands happening all the time). When you also consider that the people of the city watch crucible matches themselves for entertainment its far more conceivable that they are run like your own local sporting events (a few happen each week) I assuming this post is mainly satire but if you ignore the break in immersion this makes perfect sense. Its like asking "If im the Hivebane, who are the people in my fireteam?" the answer is that they are random Guardians AND ALSO the Hivebane themselves in their own Destiny universe. This is also how everyone can have an Exotic weapon, there supposed to be one of a kind be everyone can get it