Well, a mono synth isn't suitable do play a real music score, even 2 voices are quite minimalistic.
But I think what makes it even more powerful is the fact, that the Paula Chip can invoke an interrupt everytime a pair of samples is played back. So, having a little CPU involved, you can do AM, FM, WaveShaping etc. even with 4 Channels. And I think this was sometimes used in game music.
