Why does the development section of sonata form often move through several different keys?

In sonata form, the development section serves as an area of tonal flux where the composer explores and resolves the conflicts of tonality and theme established in the exposition.1

The primary reason the development section moves through several different keys is to create a sense of harmonic instability. By rapidly modulating through various keys—often settling in regions only distantly related to the original tonic—the composer builds musical tension. This instability is essential to the dramatic structure of the movement; it serves to cast the eventual return to the home key in the recapitulation in a much stronger, more satisfying light.213

Essentially, the development section uses this rapid harmonic motion to contrast with the stability of the tonic, ensuring that the final resolution back to the home key provides a powerful sense of arrival and closure.32