Wait, I can. Check this out. What might have been.
HAM4 would only have 2 bits for command data (as the other two bits are: select palette, change R, change G, change B). So you would have a four colour palette (full 4096 colours) and the ability to change a colour channel's top two bits (severely limiting the range of colours you could select). You simply wouldn't have been able to get any kind of smooth gradient or decent pictures, and you would have been better off with EHB with copper palette changes in most cases.
