The reality is that self-publishing as well as traditional publishing requires marketing. How can anyone buy a book if they do not know it exists.
With today’s social media connections, local newspapers, blogs, book clubs and library signings there are many opportunities to promote a title.
Other authors are doing it. It makes sense to be competitive, even if you have a traditional publisher behind your book, that the author should do as much to make the audience aware that a book has arrived.
As for the book in the forest. Someone might read it, if there are signs pointing to its location.