The poster hadn't quite became a household item yet.
not true Anthony.
all through the 1800s it was very popular to have portraits of Geo Washington (aka poster prints), large maps, art posters, Lilly Langtree posters, posters of their favorite stage actors, William Shakespeare, Revolutionary or Civil War scenes, classic renaissance paintings done as prints.. there were lots of subjects that people had posters displayed and they were always the focal point of a home or establishment (like saloons), they just weren't called posters at the time
what these items had in common for the most part was that they were either famous scenes or portraits.
show or stage posters were plain broadsides with lots of text and maybe a small b&w portrait of a star
Actual posters of course really don't become interesting until color lithography becomes more cheaply available, increasing propagation into popular culture and becoming a stage for artists like Gustav Klimt, Toulouse Lautrec and Henri Fantin-Latour. This was the point at which it becomes common for a larger audience to more easily buy posters as the prices became affordable and the subject matter expanded. Probably the most common type of poster in someone's home in the 1920s, by which time color printing had afforded a preponderance of society to afford posters for the home, would be the illustrated calendar with a huge homey print, an image of a pinup girl, a railroad image or touristy location