That’s probably because the definition is a personal one. In the very literal sense of the word, a headline baiting you into clicking onto it needlessly is clickbait. It baited you into clicking.

And while the author is free to use a very narrow definition, it’s entirely reasonable - and has as far as I can tell become the norm - to define it as any headline where the article only says something that would have trivially fit into the headline to begin with.

So for example, this very article could be better titled “Clickbait has made video game headlines exhausting to read”, and without being longer it would convey the crucial part of information - why is it exhausting?! - without someone having to first open and scan the article. Which, if the article were well-written, they’d still want to do, assuming the subject matter is of interest to them.
And that’s the thing: clickbait precludes being allowed this choice. By not telling you the crucial piece of information, you are forced to open the article (generating ad impressions!) to find out whether you want to read it or not, often wasting time diagonally scanning said article.