James Maliszewski points out that D&D always had “mook” rules:
Under OD&D, a fighting man can attack a number of times equal to his level when facing foes of 1 Hit Die or lower. This rule carried over into AD&D in modified form, with multiple attacks being allowed only against foes of less than 1 Hit Die.
I'd completely forgotten that, if I ever knew. That's tremendously interesting.