I am skeptical on the point that a good publishers adds no value.
In our case, we authors have been publishing papers for over a decade. And together we have almost 1000 citations for our papers.
And yet, we were not able to think over and improve on certain aspects of a book that we discovered only after talking to our current publisher.
Maybe if you are completely clear on what your book is about and how will readers react to it, a publisher might not matter. But for us, it seems it was not the case.
In our case, we authors have been publishing papers for over a decade. And together we have almost 1000 citations for our papers.
And yet, we were not able to think over and improve on certain aspects of a book that we discovered only after talking to our current publisher.
Maybe if you are completely clear on what your book is about and how will readers react to it, a publisher might not matter. But for us, it seems it was not the case.