Right, but if your tune mostly uses conventional major and minor scales (which most do!) you mostly won’t need accidentals.
Also, you’ll be able to transpose to any other key just by shifting the letter names up or down and changing the key signature. That’s a really interesting and useful property.
Also also, the notes with accidentals won’t change when you transpose (although the accidentals themselves will need rewriting).
Transposing music would be hellish without this system!
