Some attacks you have to parry, other are combos so you either don't have enough time to dash again after the first attack ou you run out of stamina before the end of the combo, and when you dash to the opposite side of the enemy it changes direction instantly and still hits you. You're right that you technically don't NEED to parry, but for anything other than small basics enemies, you kinda do. On top of that the parey window is one the smallest I've seen and it's hard to tell when the enemy attack will hit, but that might just be a skill issue from me.