Not only is it not silly, it is legally required. Judges and juries are prohibited from applying the standard of proof to individual pieces of evidence. They must apply that standard only to the whole of the evidence.
Which doesn't preclude that they can't look at the authenticity, validity and credibility of those individual pieces of evidence.
Nobody is saying that each individual piece of evidence has to be conclusive beyond a reasonable doubt, but when much of the evidence isn't credible or non-persuasive the whole of the evidence will not meet the standard of proof.