If Paul and John weren't in any way unusual, The Beatles wouldn't have been that special a band. I think it's absolutely justified to discuss a particularly talented musician's mind.
Of course there are many good musicians who can play a tune immediately after hearing in (if you want to see this in action, check out Rick Beato or Justin Hawkins on Youtube), but having heard it once decades ago, not knowing what the song is or who it's from, trying to find out and failing, and yet perfectly reproducing it including all the verses, decades later, that's absolutely an example of a really impressive memory.
I should add but can no longer edit my reply, that these two are distinctly contrasting and somehow complementary. Notable about McCartney is that with all the success, accomplishment and tragedy in is life, he is still able to be happy. He stands as a positive example of how to be, focusing on the bright side of things, an optimist. In contrast, Lennon wasn't satisfied with anything and always had something negative to say about everything. He never seemed happy unless he was causing conflict. He was a pessimist. They seem to be two sides of the same coin of humanity, a yang and a yin that make a complete and comprehensive picture.
Both sides are important if not essential. If Lennon was instead McCartney's yes-man, McCartney's music would have suffered. Lennon's criticism made McCartney's songs better than they would have been otherwise, and McCartney's positive support allowed Lennon's music to be developed rather than abandoned.
> If Paul and John weren't in any way unusual, The Beatles wouldn't have been that special a band.
For an argument, this is question-begging, but I'm not going to argue that The Beatles were ordinary, because provably they changed music, and this is both a criticism of them and a compliment. However, for all we know, if they hadn't been so prolific in performing and marketing themselves from their earlier career, we might have missed them entirely. The more a band plays, the more familiar their music becomes, the more popular they become, the more a band plays, the more familiar their music becomes, the more popular they become, the more they play, etc.
Though it should be noted that whomever is judging these kinds of achievements of covering a song from memory isn't exactly critically comparing the original side by side with the reproduction. "It sounded exactly the same," is likely embellishment by someone without a trained ear. Picking up a song is such a common notion that it has its own idiom, namely "picking up a song."
Of course there are many good musicians who can play a tune immediately after hearing in (if you want to see this in action, check out Rick Beato or Justin Hawkins on Youtube), but having heard it once decades ago, not knowing what the song is or who it's from, trying to find out and failing, and yet perfectly reproducing it including all the verses, decades later, that's absolutely an example of a really impressive memory.