If you're in a community that has two banks, would another one help a lot? Probably not, but for sure it would if you were in an area where they have nothing. For the longest time the folks in Ear Falls didn't have a bank. They were 45 miles away. They'd drive into Red Lake for their banking.
I think postal banking would definitely be a positive thing there if it were run as a money-making operation and not at a loss.