Whether it's editors getting pressured by their publishers to show some love to certain advertising brands, or bloggers receiving free product in exchange for an Instagram pic, or friends doing each other favors, there will always be outside forces acting upon what gets included in fashion editorials and write-ups. This is the very nature of the business. But fuck, the same thing happens in government with lobbyists and powerful corporations and individuals financially backing political candidates.
This isn't to say that every "gift," favor, and business transaction is rewarded with coverage, but next time you're flipping through a magazine pay attention to the correlation between the advertisers and what's on the models in the fashion pages. Or if you ever meet an influential blogger, ask them if they only cover the products that they truly like.