Perhaps because one's world is often blue-lit? While whole-hemisphere illumination generalizes as warmer, local conditions vary. Absent direct (yellow-ish) sunlight, outdoor daylight illumination can be quite blue-ish. I've had fun recently with photos in a park under clear blue skies, shadowed by tall buildings... but with a gap, resulting in a narrow strip of bright sunlit ground. My phone will take a bit of sunlit snow as its whitepoint, and provide a blue-tinted world. Similarly for sunlit buildings in background.