Your writing is tied to what your audience knows about you. You don’t need a copywriter if you write to a niche audience who knows you and comes to you because of who you are.
You need a skilled copywriter when you write to a large audience who doesn’t know you, your product or service.
I don’t need an editor or copywriter to write an invitation letter to my wife for a date night.
The Word of God connects with us so well because the writer knows us and loves us.