I get your point, but copyright was designed to stop people stealing an authors work. The DMCA was similarly designed to help in that regard even is the implementation is somewhat questionable.

Protecting a business model such as HackerRank's was not the intention of copyright or the DMCA. Your argument almost turns the entire idea of copyright on it's head.

As I read your comment I take away a point of view of:

The HackerRank business model is predicated on keeping other peoples copyrighted work out of the hands of potential users, therefore HackerRank should be entitled the copyright of these other people.

That is not a viewpoint I could support and I don't believe many, other than HackerRank could support it either.