>>5735905they're literally not though. The patent for the original 11'' GI Joes specify that they are derivatives of dolls, but the addition of articulation is technically what differentiates a "doll" and an "action figure." So yes, technically lines like DC Superhero Girls and Monster High are Action Figures in the original sense.
Modern hard plastic action figures derive from the engineering of GI Joe, but are not actually similar to the original patented "Action Figure." Calling them "Dolls" would be like calling a human a chimpanzee.