Other “newer” stuff is rejected for the simple reason that some important “researcher” has made their reputation on something else that the new stuff might challenge. It often has nothing to do with religion. Then there is the fear of change that also impedes progress.
While there absolutely is a lot of that, for myself depending on the source, when I see a source trying to prove a much much newer date like within 10k they are making an effort to prove the Biblical new earth theory.