The short answer is to distinguish titles from the main body of text (or synopsis, lede, etc.)

It doesn’t need to be very readable because it’s used sparingly, and it’s more important that it stands out so you know what you’re reading, etc.

How to Get Attention and Keep It. The untrue story of an internet troll who thinks the damsels are lost and knights assholes trying to take advantage. by some guy whose definitely not the troll.