I don't think anyone is claiming the CIA documents that were released recently were fake so I don't think that's the case. In fact, a lot of people, even the conspiracy types, give documents from intelligence agencies a lot of weight. They just don't trust random press releases or official public statements.
As I said, there's a big difference between them saying something, and them actually publishing internal documents about the case. I mean they can always lie about the documents themselves or modify them, but there's a very long history of intelligence agencies outright lying, even in front of Congress.
There's less of a history of them modifying or altering documents that they are forced to release.
Fwiw, I believe that Oswald did it, and that there's almost no evidence for any other shooter.
The point isn't "I believe what intelligence agencies have said". The point is "it does not matter what intelligence agencies say or release. Conspiracy theorists will not trust it."
It’s called critically analyzing your sources. It’s done by tons of people including scientists and journalists. It does matter what intelligence agencies say and release, you need to know how to critically analyze what they say and release in order to intelligently distinguish between the truth and the lies.
Saying “their beliefs are unfalsifiable” is just a boring accusation. Like looking at the worst scientists and accusing all scientists that their research is bs.
The nature of a conspiracy theory is that it is a belief not-backed by facts in evidence, but one requiring the theorist to assume alternative information based on their own intuition and a distrust of official data.
Saying their beliefs are unfalsifiable is not a "accusation". It is a statement of fact.
If you arrive at your conclusion despite the evidence, then you are already relying on a process by which new evidence can be discounted.
The goal post can always be (and generally will always be) moved.
I would describe it as filling in the blanks when there is a lack of evidence. Some people do it badly, others do it well. Some people move goalposts, others don’t. You’re clearly just randomly accusing without thinking it through. I hope you see the fallacy in your thought process here.