Why isn't literature search a waste of time if centralized documentation is a better alternative?
These central repositories exists - they are called a (digital) library. What we typically mean with "doing literature review" is going into one or more digital libraries and retrieving all information on the subject. Given how heterogenous research questions, approaches, and scientific results are, it seems fundamentally impossible to provide much more structured information than that across disciplines. That said, for some fields (notably medicine, as I understand it), more fine-grained repository structures have emerged, which allow researchers to query for specific data sets etc.