Earlier quoted context omitted.
It's because of the amazing data Facebook and Instagram have to create anonymous targeting audiences with. Source: I spend millions on FB and IG ads per month.
Is your product that bad that you have to spend millions on ads just to get people interested in it? If I had to pay millions to shove my product in people’a faces because that’s the only way to get them to use it, I would reconsider whether my product should even exist.
Demand for different products is generated very differently depending on the product. Some things travel by word of mouth, some things don't.