Is that really what that option does? I recall it being there even before quick reply was introduced and mainly relating to being able to reply with a (usually predefined) message to an incoming call.
I think it does really turn quick reply feature on/off on lock screen. See also the iMore article.
I do hate it that i can't use a third party swipe keyboard (e.g. Swype) on my lock screen for quick reply. Grr.
Apple should really come up with their own swipe keyboard.