Most universities have interlibrary loan departments to obtain items outside of the university's holdings. This route would be slower, but it is legal and I sus

Most universities have interlibrary loan departments to obtain items outside of the university's holdings. This route would be slower, but it is legal and I suspect a publisher would have a hard time proving in court that someone downloaded an article on Sci-Hub rather than used their interlibrary loan service. Maybe they could get the interlibrary loan request records and check that, but I do not suspect libraries would hand those records out without good reason. And I think that is far more effort than your average publisher would be willing to put in. Plus, as the other commenter said, citing a paper unfortunately does not mean that someone has a copy of it.