Cave Johnson is a great way of putting it. Was he kinda a quack? Yeah... But, did he also advance psychology in a variety of ways? Also yeah.

A different theory I once heard is that a lot of his supposedly discredited theories about early development and fetishes/maternal attachment that arise might actually bare more truth than we realize. The caveat is that they only apply to the super isolated children of wealthy families raised by caretakers(whom Freud almost exclusively did his research on). So some of his "crackpot" theories might actually just be a window into a very specific set of humanity.