In this instance, we can replace "Proper" with "My preferred" and as a result have improved fidelity as there is sufficient information in the article and the URL to adjudicate.
I’m not speaking of preferences, but of what you’re taught to do in professsional journalism/editing programs.
Headlines are read before article bodies / before other meta-information like URLs. Often — especially when a headline is a link embedded elsewhere, but also when a headline is one among many on a multi-article layout — only the headline is read (because the reader decides they’re not interested and moves on.)
In the inverted-pyramid style of news-article structure — which is so commonplace that people intuitionally expect even non-news writing to also conform to it — a reader is supposed to be able to stop at any point in reading and have received all the important info; and an editor is supposed to be able to cut any article from the bottom up for space reasons without damaging the article’s meaning.
Thus, readers expect a headline to be a most-condensed summary for an article; something they can read without reading anything else, and still come away informed.
This leads to guidance for writers of headlines, even in non-news traditions: write the headline such that a reader can read a headline, decide they now know enough, and stop reading/move onto something else, without doing so having resulted in the reader being misled.
An article whose headline is a quotation, but which does not quote the quotation, is misleading to those readers who read nothing else. This is, from the headline-writer’s perspective, bad praxis.
That might be a good argument if this was a news website. It's not a news site though, it's a website that investigates sayings. The saying is the title of the essay. You can feel however you want about quotations in the headlines of news articles, but it's irrelevant here.
While you can argue the person who posted it here should have included quotes, the author posted it on their site where anyone visiting would not find it misleading.
Although magazine and newspaper feature writing is not necessarily inverted pyramid.
Something resembling inverted pyramid is often a good style for news because a reader can stop at any point. But historically it was at least as much for editors as readers because it meant that in layout the could cut an article--especially wire service copy--at pretty much any arbitrary point.
And as for headlines it varies. A magazine like The Economist for example, in their print edition, often goes for cleverness in headlines (although they also have a dek that summarizes the article in a more straightforward way).
