In my childhood, slide shows were very deliberately curated, in no small part because the presentation of the slides was a relatively elaborate, shared family event.

But curation was done mainly by the creators, who were the people who were able to do the creation in the first place (professional photographers, people who could afford to buy the expensive camera, people who could afford the software for editing photos/slideshows in mass etc.). Now everyone can curate, and consumers can actually pick which curated collection is truly the best.