The entire point of academia is to extend the current state of knowledge. When judging if a paper is extending knowledge, the reader must understand 1) what the prior work is and 2) how the author has extended prior work. Without citing prior work, how is the reader supposed to tell what the author has done new?

Not only that, reproducibility is core to research. Without having detailed records of where ideas are originating (i.e., citations) research is much less reproducible.

There are actually many examples of papers getting accepted because the authors claim something new by using new terminology, but ignore all prior work in the field. The reviewers are not experts in that subfield, so they accept the paper without realizing it is not novel.