Have you ever noticed that sometimes when you are playing a piece, your fingers just start playing without you really having to think about what you are doing? That’s because you have developed muscle memory for that particular piece. Your fingers have essentially “memorized” how to play that particular section of the song.
When first learning piano, or any instrument for that matter, you want to learn the names of the notes on the staff. Knowing the note names will allow you to further your skills with music theory, sight reading, analysis, and so on.