Should a beginner use simplified (easy) version?
I found a similar question
but additionally, does it impede your progress? I mean I heard that it's not bad to challenge yourself to improve so that's why. I could use some more elaborate answer.
what if a professional pianist purposefully chooses to use a simplified arrangement?
There certainly have been cases where professional pianists have played simplified versions of pieces.
For example, there are some quite famous pianists with hands significantly smaller than Rachmaninov was blessed with, and played slightly altered versions of some of his pieces, such as playing arpeggiated chords instead of straightforward chords, or even omitting a note from a chord which their hands simply could not reach (at least without impractical contortions).
If done carefully, such as keeping all the essential notes of a chord, and omitting a note which is actually played an octave higher or lower, maybe in the other hand, then the change is not overly noticeable, and the "simplified version" still maintains the essential character of the original.
In the case of someone learning to play piano, I would say that playing simplified versions would not impede progress, so long as the simplified version still maintains the essential character of the original. In terms of challenging yourself, in the case of some of the super-hard repertoire, then a (slightly) simplified version could still be sufficiently challenging!
The important point is to play pieces where the technical and musical challenges match (or slightly stretch) your current ability.
If you want to play simplified versions of more difficult pieces, that's fine. If you want to play pieces where the original version is technically easy (and there are plenty available) that's also fine.
The main problem with "simplified versions" is when they are poor quality simplified versions. Anybody can delete half the notes in a piece and publish what is left, but the result isn't going to sound very good, and learning it may not improve either your technique, or your musicality. If your musical diet is the equivalent of living on coke and burgers, you have a problem!
Also, note there is plenty of original music which is not particularly technically challenging, but certainly musically challenging to play well - for example, pretty much everything that Mozart ever wrote for piano.
If a professional pianist only had access to the score of a "simplified" version of a piece that they are required to play, he/she wouldn't necessarily play exactly what was written on the page, if adding things to the simplified arrangement made it sound better. The difference between professionals and non-professionals is that a professional should be able to make any piece of sheet music put in front of them sound good, with minimal rehearsal time - that's what they get paid for!
As a beginner, one has to play simplified versions of complex pieces. Yes, challenge yourself, but don't try to run before you can crawl. A complex piece is just that - complicated and difficult. For a beginner, it's probably too difficult for many reasons, so a simplified version is appropriate at this time. As progression is made, other appropriately challenging pieces can be tried, but they must be achievable at whatever level, otherwise what's the point?
Yes, complex pieces are played in a (slightly) simplified way, due to physical restrictions of the player, but that's a different issue altogether.
