Why isn't literature search a waste of time if centralized documentation is a better alternative? I am asking this question regarding to the documents (thesis, research papers, and publications) that contain original, novel work.

Before starting to write a research paper/ thesis, searching for a problem statement, submitting to a journal, staring research work for Ph.D., etc., every researcher has to do a proper literature search. It is a well-known fact that literature search is mandatory for every professional researcher.

There is a finite number of existing disciplines and each discipline has a finite number of existing topics to research and to publish upon. Why is there no centralized mechanism to document the research that has happened till the previous year? If the discipline or topic is totally new anyway there is no need for the literature search.

If there is such a mechanism, then there is almost no chance for rediscoveries and there is no need to search for the whole literature that is randomly distributed across the Internet, paid journals, libraries, etc.
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.