You might be asking yourself, “So, do I really have to learn music theory to learn how to play piano?”
The quick answer? No. Some people don’t get music theory, don’t want to know music theory, and sight read well enough that they don’t really need it anyway.
However, piano more than any other instrument can benefit from a music theory teaching approach. The keys all sit there before you. However, this means that musical patterns get lost for many pianists, and theory is all about patterns.
I like to use this analogy. On piano you can see the trees easier than the forest, but on guitar you can see the forest easier than the trees. The trees here represent the notes while the forest represents the patterns.
On guitar, you can easily move around using patterns. Once you’ve learned a moveable scale or chord shape, you can easily move it up and down the neck. However, doing this you’ll likely lose track of the notes.
Conversely, on piano you’ll become hyperaware of the notes, but can lose the patterns. Every time you play a scale, chord, or arpeggio, you’ll need to know what notes you’ll be playing. But the layout of the keyboard, especially the missing black keys between E & F and B & C, obscures many of the patterns on the piano.
The patterns that music theory reveals will help you sight read, improvise, and compose better. This is really why you have to learn music theory to learn how to play piano. Because it will make you a better pianist.