Expedience

Grad school committees outsource a lot of their admission decisions to the GRE, although GRE scores are not precise measures of student potential.

Search committees outsource a lot of their decisions to the editorial boards of Science and Nature and Cell, although glamour mag publications are not precise measures of faculty prospects.

Tenure committees outsource a lot of their decisions to federal grant agencies and, increasingly, to external reviewers. But with funding rates so low, there is a huge amount of luck in getting an external grant.

We use these metrics not because they are precise (though we pretend they are) but because they are expedient. They let admissions committees, search committees, and tenure committees be lazy and make decisions without the hard work of reading deeply into the narrative provided by the applicants. They are convenient ways to cut stacks of applications. The let committees kick the can of responsibility down the road.

Given the numbers of files that committees are often supposed to read, it’s understandable that people want shortcuts. But don't mistake a shortcut for a precise and meaningful assessment.