Not least of the reasons is market segmentation. They want their marketing to be able to easily target narrow segments of consumers, and one of the easiest ways

Not least of the reasons is market segmentation. They want their marketing to be able to easily target narrow segments of consumers, and one of the easiest ways to do that is to make sure the consumers are already segmented. If Google comes to them and says "we want to run ads for our phones", CN puts the resulting ads in Wired. If Google later comes back and says "we want a piece about the menstrual tracking on our Fitbits", CN can say "no problem, let us put an ad in Vogue". It also lets them optimize the shared infrastructure. The content in Wired and Vogue isn't all that similar, but the basic printing of magazines doesn't change enormously depending on what's printed on the pages. And I can't find anything specific, but I'd be surprised if Wired and Vogue didn't go to print at different times of the month.