I would imagine that they took the best GPU chip they could afford the space and power for, and found that 8 channels was enough for 99% of their customers? I

I would imagine that they took the best GPU chip they could afford the space and power for, and found that 8 channels was enough for 99% of their customers? I assume adding more channels takes space, perhaps the GPU would have had to be lower performance to add more channels? (speculating)