Why? An emulator isn't legally any different than a virtual machine.

Low-level emulators can be legally identical to a virtual machine, but often isn't. Most modern consoles can't be emulated that way, and most require you to dump a bootrom from your own console hardware, alongside game keys and other dubious digital paraphernalia.

Just like a PC, bare hardware without firmware or a boot OS is pretty useless. Same with emulators.

Most distribute a pretty wide range of stuff along with them.