I discovered that there were roughly three times as many colo[u]rs in the USA vs the UK when I moved 20 years ago. But thanks to globalization I bet they have Aqua and Taupe in Blighty now...
Move to Finland, there are far fewer colour-names there!
(UK definitely has taupe these days, "aqua" sounds like the kind of name a paint-salesperson we use!)
> naming the sky's color is quite a useless act.
The sky's colour varies greatly. Blue, blue-white, white, light grey, dark grey, yellow, red, purple, black-with-whitish-pinpoints. Probably more, but those are just the ones off the top of my head.
Blue is not a color that used to appear often on daily objects, and naming the sky's color is quite a useless act.