Because it's a Super Mario parody, and fanon villains aren't allowed here.

Yet I’ve seen smg4 villains here?

^ Actual SMG4 villains or GLITCH Production villains?

Actual smg4

Waluigi

Francis ( who’s originally from one of the first few paper Mario games as far as I’m aware )

SMG3 ( when he was still a villain he was still a Mario recolor but idk if that counts )

And in western spaghetti one shot wren is a inkling ( but other then that it’s original ( well somewhat )

And villager in early SMG4 ( and a few others but those were one offs in early smg4 so those don’t count )

^ Weird. I should probably have those pages marked for deletion.