The point is summed up in this paragraph:
The lack of research interest in HR stems partly from carving up the topic into so many subfields. There are separate associations for labor economists, sociologists, and psychologists that look at the same problems, but these specialists don’t seem to be aware of one another’s efforts, let alone work together on solutions to our talent problems.
https://hbr.org/2015/07/b-schools-arent-bothering-to-produce-hr-experts
The consequence is that most companies seem to rely on other fields, such as data analysis, to solve what should be in the HR domain.