Because parenting is a 24/7 thing. It’s not just a thing you do when a child Needs To Be Parented. You are a parent all the time, and this should affect what kind of PERSON you are. Your child looks up to you, and you need to put in the work to SHOW them how to be a good person, and that is a constant, never-ceasing job.
Otherwise you’re not teaching your child respect. You’re teaching them obedience. And personally, there are more important things I’d like my child to learn–like for one thing, to never let someone lay hands on them.