My ideal reader or muse, no, not me

I just read an essay about the ideal reader. They were saying that all writers write to someone. I was told this a long time ago in a creative writing class and I would say it was the one main thing responsible for me not writing for years. I couldn’t define that person, who they were. I stopped writing as I thought I needed to find that reader to address.
All these years later, getting annoyed reading that essay, I discover what I actually do. I don’t write to anyone but my characters. I owe it to them to build their life in the story. I address the writing to them by building their life and reason to be. I owe it to them. I owe it to them to enter into their heads, not the readers heads. If I extract the human from my characters then that is what will resonate with the readers, not pandering to an assumed market, body of people, or Mrs Baggins of 3 Cherry Road, Basingstoke.