I mean your view of which facts from an article are worth emphasizing. There are infinitely many facts*, and they don't select themselves. People do that, based on their views.
> If I can't post the line then it looks like I'm just reposting the terms
I hear you, and yes there's an upside when the title explains why the article is being posted. But there's a downside to letting submitters editorialize titles according to what they themselves think or feel. Titles are the biggest influence on threads by far, so this is important.
Basically it's a tradeoff, with no perfect solution. The optimal solution (that we know of) is what I described above: post a comment explaining why you posted the article.
* https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...