Double-sharps are actually a great example of syntax for experts being inappropriate for novices. The double-sharp on a note indicates that that particular note is part of an upward motion. Writing the same note as the equivalent natural would instead indicate downward motion (assuming a sharp key). Knowing the intended motion of a note can influence phrasing and help a reader predict the next note of the melody without looking ahead.

Of course when you start out reading notes, double-sharps are confusing as heck.