GC emulation wasn't emulation; it was done with a separate chip. It was more like native support. Eventually Nintendo removed that chip and backward-compatibility support from the console.
(so, even if you could put a GC disk in, it didn't have capability to natively play the game)
It sounds like you're confusing the Wii's backwards compatibility with the PS3's. The Wii didn't have a separate "GameCube chip", its core was effectively an overclocked GC.
He explains it quite well. Sorry itβs German but I guess the information about the chips and reasons Nintendo choose them should be all over the net.
Similarly, a lot of the SNES internally looks like it was at least initially designed for back compat with the NES.