Games can be hidden for a variety of reasons.

The process for checking for news about these hidden games is complicated.
You have to go to View, Hidden Games, and then the game in that order to access new information.

This isn't a problem if you only own one or two games, but the problem is that if you own a lot of games, checking them one by one takes too long.

That's why it would be nice to be able to add a newsletter to the hidden games list, just like the existing library.