I-79 runs north south from top to bottom. PA 65 goes from right to left.
This interchange is done this way due to PA 65 running beside railroad tracks. So the exit ramps have to come into PA 65 on the north side. But what complicates matters is that I-79 goes through a valley here so the ramps are restricted to the size of the valley. This interchange would become more unusual if the rest of the ramps could be added.