Uh, that isn't the rule, for exactly that reason.

> Otherwise please use the original title, unless it is misleading or linkbait; don't editorialize.

https://news.ycombinator.com/newsguidelines.html

I've seen many cases where mods revert an informative title in favor of a less informative one. Also, the idea that the title of a submission should match the title of the resulting article is quite silly, since often the article is written for a different audience and the informed HN submitter can sometimes craft a title that better summarizes to HN readers why the story is interesting / worth reading / controversial.