So Much For 'Primary Source' Material (at least, at times!)

Though I have taught certain aspects of history, I am grateful that I am primarily a musician, not a history teacher, what with revisionism, speculation and the like constantly being partners in this pursuance.
To cite (even though this event is not of earth-shattering dimension):
I have heard three different interviews given by the great pianist , Vladimir Horowitz, about the same incident (two of which I have on film); specifically, when he was a child, the first remembrance of his own reaction to music was his incessant tapping of his fingers on surfaces. On one occasion, he was tapping on a window which broke, causing blood to flow from his hand. In one of the interviews, he claims he was around three years of age. On the other interview I have on film, he was four years of age. And in a third interview I saw on television, he had his age centered around two years.
Another example of primary source experience centers around the fabled pianist, Artur Rubinstein, who while reminiscing about musicians he had heard, singled out the composer Claude Debussy. Rubinstein, as a youth, remembers Debussy as "one of the greatest pianists I have ever heard".
The recordings of Debussy I know of, especially from the Vorsetzer period I have written about, demonstrate that at best he was facile and rather indifferent; certainly, in my view, not a great pianist.
And having just seen a documentary centering around the death of Josef Stalin in 1953, and a documentary loaded with contemporaries of the tyrant and the children thereof, it was nothing but an hour of "it's possible that-", or, 'what if", or, "what truly might have been". or, "these are the possible results", etc., etc.
So; at least at times, so much for Primary Source!