An editor is like a professional reader, and as I became a better reader, I also became a better writer.
I was a book editor for nine years. I'm familiar with the opposite experience, bracing myself for the likelihood that no one would want to publish my book.
Working as an editor was like being a professional reader, and the better I became at reading the better I became at writing.
To be a good editor or a good writer, I think you really need to be a great reader first.