Newspaper layouts, punctuation and more

I've been looking for comments and information on the trend adopted by some newspapers and magazines regarding kickers, straplines, or whatever they're called, like this:

Note that this journalistic device does not match the definitions given below or elsewhere.

More particularly I was hoping to stumble upon an explanation of why this device is punctuated the way it is, i.e. with no full stop (or period).
I haven't had much success, but here are some of the items located so far:

The FT on its own new layout (15 September 2014 issue): New look for Financial Times newspaper.

From The Wall Street Journal: Punctuation Nerds Stopped by Obama Slogan, 'Forward.', subtitled From Both Sides of the Aisle, a Question: Is Ending It With a Period Weird?

'Strapline', 'crosshead', 'standfirst' and 'pull quote' defined and discussed under the heading
6 newspaper writing techniques for the web. Example:
Standfirsts are short (1 or 2 sentence) summaries of the complete text.

Update (26 April 2021)

The absence of a full stop at the end of a standfirst is sometimes justified by the claim that it functions as a subheading. To my mind, it depends on the layout and the number of words. If the standfirst is just a few words, the absence of punctuation may be justified. If it is longer, it simply doesn't work for me. If it's more than one sentence -- which is typically the case with chapôs translated from French -- I always ask the layout team to retain a full stop as a strong personal preference.

Among the definitions offered by Elements of a newspaper:

Kicker: Kicker is the headline that is written on top of the main headline. It is set in a point size that is less than the point size used to set the main headline. In several newspapers the Kicker is called Shoulder.
Strapline: Strapline is a headline written beneath the main headline. It is written in a point size that is smaller than the point size used to write the main headline, and is generally used to highlight a new point. It can also be used to amplify the main headline. In some newspapers, Strap-line is also referred to as Reverse Shoulder.
Infographic: An infographic is an art form where words are used with charts, illustrations, graphs or photographs to tell a news story.

On taglines, including tagline punctuation: Tagline blues.

30 Awesome Newspaper Layout Examples & Tips
and
30 Stylish Examples of Layouts in Magazine Design
include examples from various countries in various languages.