No one said one is REQUIRED to use intercessory prayer. On the contrary, in my previous post, you will find I said one can pray directly to any of the three Persons of the Trinity. We do so in the Our Father.
Second, reiterating above, intercessory prayer isn’t required. However, we ask our fellow man for intercessory prayer. Why? Because we seek and give spiritual support to our neighbors. We are showing them true charity (Caritas, or Agape).
Was Paul’s teaching only valid for the time, place, and people it was written to? No, nor was any epistle. Rather, they provide constant teaching to men everywhere, and for all time, as it was inspired by the Holy Spirit.
Including me. I never claimed catholics said they are required to do so. I merely asked "why do so?"