The IPTC Metadata Standard defines the “Title” attribute like this:
A shorthand reference for the digital image. Title provides a short human readable name which can be a text and/or numeric reference. It is not the same as Headline. Enter a short verbal and human readable name for the image, this may be the file name
And here’s the definition of “Headline”:
A brief synopsis of the caption. Headline is not the same as Title. Enter a brief publishable synopsis or summary of the contents of the image
This to me says that gallery services like Flickr or Facebook should display the Headline field from uploaded photos, not the Title. They don’t, so I’ve had to resort to contortions in order to work both the way I think things should work and the way they actually do work.
I give up. I’m now entering descriptive text in the Title field rather than the Headline. Hell, in Lightroom CC there is no Headline field. It’s turning out to be way easier to do it wrong like everyone else. Who knows, maybe I’m the one who’s been wrong all along.