Null hypothesis is the soul of any hypothesis and it is the null hypothesis on which we accept or reject our hypothesis, whereas in many social or business related articles these are not included.
Not all investigations required an hypothesis. The investigator need capacity to determinate if it's convenient or not, but it's mediated by kind of research.
Null hypothesis is often applied on undergraduate level for better understanding of what hypothesis is. In professional research null pyotheses (and alternative hypotheses) are replaced by research questions based on some specific observations or identification of caveats, gaps, or niche.