Adapted from a comment I posted in a dialogue with “dwstroudmd,” a commenter at T19:
Setting up the analogy
Suppose that I, having only basic first-aid training, were to insist that it didn’t matter whether first-century Jewish midwives washed their hands before delivering babies. According to me (let’s suppose), the extant religious standards called for all devout Jews to wash regularly. Surely that would have been enough to guard against infant mortality and death in childbed, right?
You, an experienced modern-day obstetrician, would smile tolerantly, or even laugh. And rightly so: If I’d had the benefit of your training, I’d have known that your profession has established (not without controversy) that mother- and baby-killing infections can sneak in via even the cleanest-looking unwashed hands.
(We can’t mock first-century midwives for not knowing this, though; they lacked the necessary underlying knowledge about infectious microbes and their transmission.)
Ancient storytelling practices weren't necessarily a sufficient guard against distortion, just as ancient sanitary practices weren’t necessarily a sufficient guard against infection
Now let’s reverse the roles. Certain modern theologians make the claim that it doesn’t matter whether the NT accounts are hearsay, or (if in fact they were eyewitness accounts) whether they were first written down decades after the witnesses’ observations, without the opportunity to dig into what the witnesses actually saw as opposed to what they claimed they saw.
According to these theologians, various first-century storytelling practices — "sanitation" practices, if you will — would have been enough to guard against distortion of the NT tales, even the most extraordinary ones.
It turns out, though, that at least so far as we can tell) these theologians have little or no training in interviewing actual, fallible human witnesses (let alone in cases having real-world consequences).
Our modern theologians apparently know little of the the vicissitudes of human perception and memory, as demonstrated convincingly by modern journalists, police detectives, and lawyers, not to mention by experimental psychologists.
That might give you an idea why I react the way I do when reasserters make such grandiose claims: When you [reasserters] make such confident assertions about first-century storytelling practices, to me it sounds just like a non-physician who claims that first-century midwives didn’t need to wash their hands.