The important part is that backwards compatibility became a focus after the Gamecube and it has been ever since. Like, this is just a fact. The Wii supported Gamecube games and controllers. Even the WiiU had the internal capability to run GC games, it just lacked the disc drive for it, and it ran Wii games just fine. The same goes for every single of their portable consoles (GB games work on the GBC, GB and GBC games work on the GBA, GBA games work on the Nintendo DS, etc).
