Oooookkkaaayyy. I'll answer your inquiry at face value. Basically you can imagine that most students take about ten to fifteen years of piano lessons until they are done gr. 10 piano. That's when they're usually about ready for the Chopin Etudes. So they start with a primer book first in order to learn the names of the notes, timing, phrasing, and very basic articulation. Then they start two-handed music by beginning with such things as parallel entries or chords that support only a portion of the melodic phrase. Then they learn other finer points of articulation, and more two-handed work including rounds in which lines of music overlap at a bar-or-so's distance. For the remainder of their piano career, they continue adding complexities, such as playing one hand legato, while the other hand staccato; or holding down certain fingers while releasing others; or being able to assimilate many chords(using up to about nine fingers at a time) fast enough to stay in tempo; or playing many notes in complex rhythmic patterns. There's also dynamics and shading, and shaping to think about, and questions of notation, and a myriad of other details.
Mnay beginners could learn a piece in terms of the notes if they were forced to, say if they could only get out of a labor camp if their Chopin Etudes were up to snuff; but making it music is another matter. For another comparison, think of the medical world.
If I decided to perform a gallbladder operation on myself, there would be several people who could teach me how to do the cutting, how to unhinge it from the rest of me, and how to sew it all up. But what about finer points, like what to do if I start bleeding to death, how to avoid infection, and how to avoid the whole situation of self-operation in the first place?
People should not aim for unrealistic goals when thousands of realistic goals can keep them busy for days.
A beginner should not waste time musing about Chopin Etudes, or Fur Elise, or the Moonlight Sonata to name a few.
Hope this answers your question.
Anja, B. Mus, and student of piano for 30 years.