Imagine a 100 metres tall wardemon from the very very scary shores of hell hits you and wont 1-shot you.
If you take away the damage from the Lilith orbs you can hand over the joypad/keyboard/mouse/mice to your cat and she/he will crush her.
At one point at the game there have to be 1-shot mechanics or you would be able to sit out the hardest content behind your armor and/or anxious bubble (palidan shield).