There were elite leaders who had access to more than one author, true.
Again, think of the masses, think of the entire Christian population.
Many only heard from ONE Church Father due to the manuscripts or Scripture that was available in that geographic area.
It is completely absurd to say that, since ONE person, or even 100 people, had access to more than one NT “Book” that ALL Christians had the same.
It is not absurd given the apostles, specifically Paul, Peter and later John worked extensively in the churches. Most of these early churches had scrolls from synagogues. Jesus told the disciples they could find Him in the OT. Again the example of Polycarp’s epistle shows a wide use of multiple NT books. 17 of 27 used.