Um, yes, yes it is our job
...to pass judgment on information. That's what we do. We select and de-select materials. We do literature searches for customers, judge relevance, and present only the most relevant results. (Yes, I know about arguments about relevance, but anyway).
Catalogers and indexers also pass judgment -- what is the best description of the document? How will users look for this material? What is the subject that best describes the content?
We can't possibly buy all of the books published, so we use our professional judgment to pick only the books that are the best and potentially the most useful to our customers. When the books are no longer useful, we ditch them.
In fact, it's this professional judgment that prevents libraries from weeding Silent Spring
or a number of other classics -- even if they don't circulate regularly. (Incidentally, in my county, Silent Spring
has been on the required reading lists of high schoolers for a long time so it is very heavily circulated). The classics are kept -- normally 10 or so copies per branch for all of the ones that ever get on reading lists.