The issue with the Defensive fighting style is the same issue with shields: most players prefer to be aggressive than defensive, even if it's the wrong choice. Think about how many times you've seen a melee character either dash or throw a weapon at disadvantage (from range). I'd bet most of those times it would have been smarter for the character to dodge instead. This is especially stupid when the enemy doesn't have any ranged attacks either, but that never seems to stop them. Leroy Jenkins was around long before the internet, he just gave it a name...