That's a logical fallacy. You cannot possibly interpret the reasons why people use the social networks. They very well may feel forced to use them in order to get a job or otherwise be socially accepted. You call that "value" perhaps - they use it to get a job, therefore providing value. But that is an intentionally misleading line of thought and leaves the reader less informed than when they started reading.

The situation is a lot more complex than "providing value". People use social networks because they have been artificially forced into society as a near-necessity. Our society does not actually need them. But because we have them, people must use them. That they use them does not mean they derive value from them. They may not see it that way (I don't), and in aggregate, it does not seem to provide value to society at all. I would even argue that social networks have provided detrimental effects to society overall, and produced negative value.