Their main purpose may be seen as an object to prevent spillage when pouring a dram, but they also serves a purpose of making any brand more visible on a crowded back counter of a bar where labels may not be seen.
Like water jugs they are advertising space with a purpose.
I'm not sure when they first came into use, but it's easy to spot the really old ones dating to pre 1950 as they mostly have a circular metal holder for the label.
In the -60's and -70's the most common type was made of ceramic and made by the same major companies that made/make water jugs, like Wade and HCW. Harder to date as this type is still in production for brands that want more "class" than what they get with the all plastic ones that became common from late -70's.