Who else would have? James, an apostle, led the church of Jerusalem until his death when Symeon succeeded him. Certainly St Paul left someone in charge of the churches he founded when leaving to preach elsewhere, and St Paul also tells of the requirements for Bishops.
That's not what Scripture shows. Paul never directly appointed a Bishop. He always put his authority equal to or behind the local leaders of a church. He taught what the qualities a congregation should look for in a leader, especially charismatic gifts.