Actually maybe it's an American practice less common in the U.K., but I actually edit to this standard. The usual U.S. style-guide preference (See what I did there, lol?) is to place a hyphen between two nouns when the nouns combine to describe another noun. Or you can think of it as the two hyphenated nouns doing the work of an adjective.

Sorry to be pedantic! As I say, this U.S. grammar guideline might not be as common elsewhere.