I want to thank our favorite conspiracy theorist (e.g., Henriboy) for providing this forum with a prime example of the Bellwether Fallacy. The Bellwether Fallacy is a common pattern of argumentation in conspiracy theories. Most conspiracy theories are, to a large extent, theories of history. That is, history tells us that something happened, but a conspiracy theory says that some other (typically poorly defined) events unfolded instead to give us that evidence.
Specifically, that something else happened instead and the evidence we have in hand is either selectively considered or has been manufactured by nefarious forces in order to keep us in the dark, lead us astray, and prevent us from determining what "really" happened. As such there are always inconsistencies and anomalies in the data. Historical events never leave antiseptic data sets that point inexorably toward a single conclusion to the exclusion of all contemplated or speculated alternatives.
Hence historical lines of reasoning talk about preponderances of evidence. And so when we dispute a conspiracy theory, we point back to the preponderance -- the totality of available evidence that en masse suggests a particular cause. The essence of the Bellwether Fallacy is that one bit of evidence is made inappropriately to represent the entire question -- to become a bellwether, in essence, for a larger evidentiary picture. If the bellwether proposition can be refuted or upheld, then allegedly so goes the whole question, and the rest of the evidence is just expected to sort itself out somehow to match that direction.
MacDonald advocates have become partners in this fallacy with Helena Stoeckley being the main ingredient in this cognitive stew. MacDonald advocates have relied on the statements made by Helena Stoeckley in order to justify the position that unsourced trace evidence equals hippie home invaders. To MacDonald advocates, it doesn't really matter that unsourced synthetic fibers, hairs, dark woolen fibers, and candle wax were never linked to Stoeckley in any tangible sense.
It matters not to these same advocates that Stoeckley recanted about 50 percent of her confessions and that she testified under oath that she has no memory of her whereabouts on 2/17/70. It carries no weight with MacDonald advocates that none of her confessions match-up with one another and there seems to be a collective shrug when it is pointed out that there isn't any evidence of her presence at the crime scene.
The only thing that matters to MacDonald advocates is that Stoeckley's CLAIMS make her involvement and the involvement of others in these horrific crimes a foregone conclusion. Stoeckley and her acquaintances have to be the perps because Stoeckley said so. They add that there is evidence of her presence at the crime scene, but the CID/FBI/DOJ have conspired to manipulate, distort, and supress that evidence. All of the other more logical explanations for the household debris found at 544 Castle Drive are dismissed.
Those prosaic explanations have to be false because there is simply no getting around the fact that Stoeckley claims she was at the crime scene and that she named the "real" perps in this case. MacDonald advocates are so fixated on the unshakable notion that Stoeckley is a credible witness that they do not feel responsible for answering in detail the explanations favoring another explanation.