Because an "archive box" is a thing that is not necessarily a common occurrence in office culture around the world.

The author is Swedish. Google's translation of "archive box" is "arkivlåda". That is not a thing over here, and is not even in the dictionary. An image search for the Swedish word resulted in many boxes that looked very different.

And even if I see it as a box, it looks also like a box of printer paper to me. (It's the "Fresh paper" icon! :) )

Either way, you are diverting away from the main issue of the paragraph: Would you recognise what the icon represents even without the text?