Publishers don't do jack. The onus on selling a book is the author's responsibility. If Random House paid me $1M advance on my book, my job would be to sell it and promote it. The subversion of this is to already have a brand that is established which occurs with the first edition and again, falls back to the author.
Publisher or not, first time authors have to be marketers FIRST, authors second. Most authors fail because they remain authors and fail as marketers.