I agree, personally, I do not use the service anymore, and a quick visit to today’s home page shows a stale site showcasing “today’s” top presentations that are 4 months old. I can still remember those annual presentation design competitions a couple of years ago that attracted a lot of attention.
In retrospect, SlideShare was a mix up of a lot of businesses:
A tool to save email attachment size
A place to search for content
A curated content discovery platform
An engine that enabled you to embed presentations in web site
The service was hindered by technical limitations: somehow the quality of played back presentations was not that high, and full of SlideShare branded links and content, which is why I moved away from the platform. Recently, SlideShare killed the re-upload feature that preserved back links and view counts. Also, the acquisition by LinkedIn which then got acquired by Microsoft did not help to focus management. And finally, there are lots of other platforms out there that can host clickable slides somehow. None of them have managed to attract crowds that SlideShare could assemble though.
Ultimately, there is a market for a SlideShare-like platform I believe. And now 10 years after SlideShare was founded the economics of running the platform (storing lots of media rich content) could be fundamentally different.