yeah, actually I was starting my business just from monitoring) I am personally the owner of small instagram shop with various cosmetics and parfumes. To tell you the truth, it was actually hard at the very beginning, people had a tendency to think that my shop is kinda scam, however it's not true, of course, it hurted me so much. On the other hand, it impeded me, I decided to develop my shop and become a little more famous in my community though. The only possible solution was to buy instagram likes. It was actually the most reliable solution. Thus, I gained more than 500 followers and all of them are real people who are active on instagram. really happy that I was brave and crazy enough to pay for likes, but now I gain much more money than I paid))
As far as social media, the only way I could see it being useful is via a data scraper that can scrape an ENTIRE social media site and can breakdown the data into specific data sets via keywords to establish a natural trend, somewhat like Google Trends currently does. If you're just referring to reading through thousands of your friends post on your newsfeed then no. It works for businesses like the person above who utilizes Instagram specifically because they have a base of like minded people who volunteer the data and are a following of like minded people, their actual demographic. If you're looking to establish organic trends of an entire collective then you need a random sample of people of different circles to establish what trends are moving over all demographics.