Wood floor installation - nail AND glue?

I have 3/4" OSB subfloor. I have read that sometimes this does not hold nails well. I had an installer over for an estimate. He did not think I needed to add any plywood over the OSB but he DID say that if I were to choose flooring 4" or more in width that he would glue them down to avoid movement or cupping (probably in addition to nailing). I'm guessing if that were the case..felt would no longer be necessary. Anyway, it seems like a good idea to use both glue AND nails, so I wonder is that often done? If no, why not?