According to Quora dot com, US magazines are viewed as historically dependent on advertising revenue hence why subscriptions to magazines are historically very low as advertising is used to subsidise cover price or subscription cost.
With the general collapse of print publications in the US, particularly led by the drying up of physical newsstand presence, magazines have a harder time getting into consumer's hands. This means that advertisers are less likely to spend in a publication (readership decreasing) and then advertising revenues go down, making magazines less and less profitable.
I realize this is quit lengthy so I'd sum it up to saying the business model for magazines has traditionally been the selling of advertising space ... Not sure if this is what you're looking for
