Advertisers often use this tactic when they attempt to sell products by claiming that everyone uses and loves their products. In such cases they hope that people will accept the (purported) approval of others as a good reason to buy the product.
The not so good old Edward Bernays is the father of this concept. Thanks to the help of his uncle, Sigmund Freud, he discovered that people's subconscious desires can be used to sell them products that they don't need. He created public relations which utilizes propaganda to its full extent.
The first implementation of this was used with Aunt Jemima's cake mix. A study was done with women and how the preparation of said cake mix played with their senses.
The results were that the women didn't get an emotional lift, or any sort of satisfaction because they were simply mixing together a prepared cake mix.
As a result of their findings, Edward Bernays and his cronies, simply added an egg to the ingredients. This simple task ended up giving the women a sense of worth because it made them feel like they were doing more for their partner, thus driving their subconscious desires.
The way products are sold to us now, literally stems from adding an egg.
PS. This is my explanation, and I don't claim to be an expert
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