Even though slides have a parallel history with photos from negatives, they had a shorter time span of success concentrated essentially in the 80's and 90's, basically due to their lower cost - you could save not having to print- but also for the ability to show the images at the same time to more people, with specific viewers or projecting on a screen. The film from slides, after being developed and inserted into plastic or paper frames, was not completely protected. The film was exposed to light, touched by dust and hands, sometimes cleaned and often scratched. All this didn't necessarily compromise their duration in time but reduced the general quality of the image, so that the digital results are not comparable to those of negatives.