You do realise your sentence doesn't contradict nor negate my stance, sure he has absorbed his powers, but he never used those powers to the full potency of their capabilities, not even close.
Plus the instance you are referring to is from non canon Man of Steel comic, it was DCAU Parasyte (not canon one), rather than New Earth or New 52/Rebirth Parasyte aka canon ones.
Absorbing memories doesn't mean asborbing skills as to how to use the said specific powers, like Rogue can absorb Iron Fist's memories, doesn't mean she can automatically fight as good as IF, or another example Rogue absorbed Scarlet Witch's magic and memories, but her skills in magic were total crap in their fight, just pointing out basic examples.