A hash value is small enough to fit on one line, but it carries a large promise.
It says the evidence examined later is the evidence acquired earlier. It says the process can be checked. It gives another examiner, attorney, or court something firmer than confidence in the person who performed the work.
The number is useful because it is impersonal. Good forensic practice does not ask anyone to trust charisma. It builds a path that can be repeated, reviewed, and defended.
That is why the hash belongs in the culture of the work, not merely in its software output.