There's absolutely nothing in the article (which I did read) about it. If you yourself had read the article, you would know that it was not explained, accounte

There's absolutely nothing in the article (which I did read) about it. If you yourself had read the article, you would know that it was not explained, accounted for, or justified. There is a single vague reference to a "primary DC". There is no discussion at all of backups or disaster recovery.