Gwern commented because you said something technically wrong, even though it was essentially right. You denied that “having a large number of people telling a story makes it more likely the story is true”. But having a large number tell the story does make it more likely to be true. After all, conditioning on the story’s being false makes it less likely that a large number would be telling it (out of all possible false stories).
But your primary point remains: Often, even after conditioning on a story’s being told by millions, the probability of the story’s being true remains vanishingly small.
Gwern commented because you said something technically wrong, even though it was essentially right. You denied that “having a large number of people telling a story makes it more likely the story is true”. But having a large number tell the story does make it more likely to be true. After all, conditioning on the story’s being false makes it less likely that a large number would be telling it (out of all possible false stories).
But your primary point remains: Often, even after conditioning on a story’s being told by millions, the probability of the story’s being true remains vanishingly small.