The problem for Biden is similar to the one faced by Franken when he was forced to resign from the Senate: Descriptions of misconduct are more believable when consistent with visual evidence.
In the case of Franken, who several women accused of groping them, we had a photo in which he mocking groped a sleeping Leeann Tweeden when the two were touring together for the USO. The existence of the photo made it impossible for Franken or his defenders to dismiss Tweeden or other female accusers.
In Biden’s case, there is not just photo evidence, but video evidence of him acting creepily among younger women as VP. His antics of rubbing women’s shoulders at events, sniffing their hair, and pecking at them has been the subject of YouTube compilations for years. There’s also a photo of Biden planting his nose in the hair of actress Eva Longoria at the same fundraiser in which Flores said he took liberties with her.