That's what I meant with whether the reproduction part is the important thing. Because fiends do have cities, cultures, craftsmen, artists etc.I meant more that they reproduce sexually exclusively, ie male orcs and female orcs get together and make baby orcs and that’s how you get more orcs. Demons and devils can make offspring but it’s not how they reproduce in most cases and they don’t have infants, generally.
Basically they meet all the criteria except for making babies (and some even do this sometimes)