I think you're misreading it. In the same way as there are people that need to ride on planes (for example for their job, or to move to where they have a job, etc), there are people that need to use social media.
For example, if you own an online store you really need to have a social media presence. Same if you are an artist, and live off of commissions. I'm sure there are plenty more examples.
The original cities skylines had atrocious performance after a certain city size as well, especially on hardware available at launch. Hopefully they can deliver on better performance over the next few months, I expect it to improve before they do their console release.