What if you do not maintain such an established account (twitter, Insta, FB)? I do not understand this request.

What is this request supposed to do?
If someone sets up a hive account, then they are already in the possession of the different keys, aren't they? Why must they then confirm that they are who they are in advance/in general? Isn't that something which becomes only interesting in a case where someone already committed plagiarism/spam?

I would appreciate an explanation. Thank you.

P.S. I have read the given link of yours. Still, it does not make sense to me under this particular blog why you ask for verification since the blogger has posted quite a long story and pictures of himself. If you do not believe that its his pictures and his story from the outset, it really sounds strange that he shall give you reassurance ...?