I think it's fair to ask for such information for certain positions. You wouldn't want someone who is biased on the positions which is supposed to be neutral. Knowing that the person is biased or interests can compromise the companies projects.
On the other.hand it's completely irrelevant for the cases where guy is supposed to working on not customer facing part.
I agreed with you, in certain positions, it's totally irrelevant to request for such but then, some employers will do what they feel it's necessary
True, some employers do whatever they want without regard for standards and human rights.
I think in my next interview they gonna ask for my social media presence. Which currently is none. Talking about FB, Insta, Snapchat, Twitter.