So all those warnings on the carts are basically for nought?
Well, the warnings were meant for those users who tried to plug in cartridges backwards. (not to those disassembling the cartridge shells and removing / mixing up the boards inside them) So in reference to that, yes indeed the warnings apply because you have to use force to plug it in backwards and this excessive force puts strain on the motherboard, the cartridge shell, and the boards inside and if you force it / wiggle it too much trying to do so, you could crack the cartridge port edge connectors, or the game boards, etc.