Ex: You'll find it impossible to memorize music until you learn how to think and remember notes. Once you understand rhythm (8th notes, quarter-notes), and pitches (C, D, E, F, G, A, B C), you start to remember music.
You then study common patterns, such as Blue's Scale (C, Eb, F, F#, G, Bb). Or common chord patterns (I - vi - IV - V progression), and suddenly music is just "oh, right, the common chord progression in this rhythm".
Its not that people are memorizing more-and-more information. Its that they're memorizing __LESS__ information, but smarter information. Its far easier to remember "Loved" by The Beatles is the common-chord progression in 4/4 common time, rather than actually trying to memorize the individual notes and rhythm.
Then you can kinda-sorta forget little details (maybe play a few mistakes), but no one else remembers it as well as you do (not because your memory is better, because you have a better system of memorizing). So those little mistakes are forgotten by the audience.
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I'm playing Age of Empires 2, and the same thing for build orders. As a beginner, memorizing "2 houses -> 6 on sheep -> 4 on wood -> 7th food on boar lure -> 3rd house + mill -> 4 on berries" is difficult.
But then more advanced build orders are "British build order" is same as standard, except with 5 on sheep to handle the +25% bonus to shepherds.
It is said that you can only ever remember 7 things at a time. But those 7 things can be advanced concepts built up of *other* sets of ~7 things.