No, the Wii plays GameCube games natively. It has GameCube hardware in it. It's not emulating the games.

You're completely ignoring the difference between a natively run/performing game and the performance/bugs that appear when emulating. Even the best emulators can't give you an exact playthrough like the native console would.

There are very few emulators that do that and they're still limited to the 8 and 16-bit eras because the power required to emulate all the console's hardware to accurately run the games is immense. Almost every emulator uses tricks to get close to native performance but they don't actually emulate games the way they are played on the consoles.