I feel like this happens every month. I am looking for an answer to my issues on Splunk answers and I dig around and eventually come across a link "this was well explained at Splunk Conf 2015" and I click and sure enough dead link. Literally thousands of answers to challenges customers are now gone.
And it goes beyond that I remember helping my old boss with a his Conf 2013 presentation as well. How much culture and history was deleted? With companies so interested in their culture and brand it just seems like a bad idea all around.
I tried using the Splunk base app .Conf Archive Search (https://splunkbase.splunk.com/app/3330/) by Lily Lee which supposedly can back search, but sadly no longer functions on older sessions. And sure would be nice to even get even Splunk 2011 as well. The whole Conf history would be outstanding. But I'd take 2013 and on.
Here is a request for Splunk to restore Conf talks online.
If you could put a +10 on there and email your sales team I think we might be able to bring attention to how valuable Splunk Conf is to the Splunk community.