Any particular reason emulators are banned?

Hello all, I'm WhoDis. I'm fairly new to speedrunning, but I'm looking forward to learning a few games in the near future! These include Kirby 64, Kirby Air Ride, and Bangai-O! I also want to get into SNES rpg runs, but that's a deeeeep dark rabbit hole I won't be out of for years, I feel lol