I would say this is not at all fact but instead only anecdotal as the only real difference from bottle to bottle you should taste if age and setting (comment about glasses is right on the money) is when a particular bottle is bad. Terroir and the discerning of its characteristics relies heavily on similarity.
True up to a point, and certainly true for young wines. However, the more typical tastings of 10+ year old wines (where 2+ bottles of each wine are opened) do often show at least one wine with considerable bottle variation. It is, of course, all traced back to the cork. Whilst the wine will not be corked in the normal sense of the word, you can tell from smelling the corks that one is very different from the other. The point is that the liquid and the glass started off identical and the cork introduced the variation.