Registering to vote is pretty normal. You might not have to because the government already has records of you and that is the same in America for a lot of people. For immigrants in Europe you still have to register!
If you change municipality or state in Europe you might also have to register again so they have you voting in the right local elections.
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.