I first came across resin-coated papers while doing photography in the Air Force in 1952. The darkroom that was assigned for me to use had a big supply cabinet and one shelf was full of boxes of "rapid process" 10x10 inch paper, if my memory serves, manufactured by the Haloid Corporation. I was curious and looked up the stock number in the supply catalogue and found it was intended for reproducing aerial reconnaissance photographs. My curiosity was not entirely satisfied and I tried making a couple of prints on the paper. I was not impressed with the resulting prints and didn't like the plastic look and feel of the paper.
It was some time later that Kodak introduced the first commercial RC papers, which were immediately popular with newspapers, as well as others who liked the much faster processing, shorter wash time and rapid drying characteristics. With the introduction of Ektacolor "C" print paper the RC base allowed the entire processing after exposure to be automated and mechanized, which was adopted rapidly by photo labs, and eventually led to the "60" minute snapshot services that became ubiquitous. RC paper was all any photographer having color prints made ever saw, with the very rare exception of the few who made Dye Transfer prints.
A dozen years ago when desktop color inkjet printers first began to appear, the companies making them found photography users wanted a paper that had the look and feel of the color RC prints they were used to produced by photo labs. So, RC photo-type substrate was coated to accept an inkjet image instead of being coated with a light sensitive photographic emulsion. And today user demand remains the greatest for Resin Coated papers, even though it serves no useful, practical purpose with inkjet printing.
Considering that the fine arts photography establishment has never found prints on resin-coated paper acceptable, and an impediment to color photography prints being accepted by very many galleries and museums; and the fact resin-coated papers have not been tested for longevity and none have been given an ISO archival rating, why they remain so popular is a question.
This really came to my attention recently doing some extensive print testing with a lot of different brands and types of paper as part of a beta test or a new printer calibration and profiling system. To my eye the prints made on Resin Coated papers reproduced an inferior image compared to those made on high quality fiber-based papers, better reproducing the color information in the image file.
So, considering there is no practical or functional advantage to using RC papers with an inkjet printer, why do they remain so popular?