Question: Why are only 2 layers available for 2D mode 2?

[EthGaming101]

I'm wondering what's so important to mode 2 that it locks out two of the four background layers available. It seems like a very, very hefty restriction for the sake of being able to apply affine transformations to two layers. I'd also like to know about my options for being able to scale backgrounds (I am trying to do something similar to Nintendo Land's Donkey Kong Crash Course, where the gamepad had a magnified view of the level, while the TV showed the full view).

[EthGaming101]

Edit: I'm aware there can only be up to two affine layers at a time, I'm just wondering if standard tiled background layers can be used for the remaining two layers.

[AntonioND]

Can you tell me which function fails when in mode 2? I didn't write the original code, so I'm not 100% sure about the checks that are made depending on the video mode.