IMO, the root cause of this is companies pre-filter leaving high quality individuals to search longer. If you look at a random sample of all people to look for a job in a given year then say a long absence may be a bad sign.

However, you get a biased sample with obvious rock-stars quickly finding a job. Thus, negative signs on a resume are positively correlated with candidate quality. On the other hand resumes that look great are likely linked to people who regularly fail interviews.

PS: This is less common with collage job fairs where you get closer to a random candidate selection.