" a quick look at it on a globe reveals its true size."
True, a Flat Map cannot really show the true size of a Country, as that Country sits on the outer surface of a ball, but a flat map gives a quick idea of how many sq. miles a Country has, for some, and Greenland has a good few ! And importantly for some, the actual location of Countries, in relation to each other, and the Equator etc.
I want to get a really old fashioned Globe, just to see the errors made before Satellites etc ! As to the relative sizes of say the USA, which is, 9.834 million sq.km. and Greenland is , 2.166 million sq.km. It is far easier to appreciate this on a Globe, thanks for pointing that out LUHE ! Perhaps all Geography Classrooms should have a Globe, as in my youth, we had one at home too.