Earlier quoted context omitted.
SciHub piggybacks on the publishers' work. Stealing the output of a company and giving it away does not mean you can do their work for less.
It's the researcher who produced and typeset the article; the publisher does nothing more than hosting PDFs sent directly from the authors after they passed peer review, which is not something the publisher is involved with.
See http://www.nature.com/news/open-access-the-true-cost-of-scie... for a good overview of all the sides here.