I've seen questions and answers about the "when", but I don't really understand the reason to use this Horrible Way to Type Sentences Which Obviously Hinders Readability. It's really bad when in a newspaper or on a site you see an article with a long title with names and unique terms which are normally capitalized, and in certain contexts may look ambiguous and confusing, especially when common words are used in product names. Sometimes you don't know right away where a thing's name starts and where it ends.
Why was title case invented in the first place? What problem does this style of writing solve? Does that same problem exist still in the modern world? And does it apply to electronic media which didn't exist back then?