Every time someone at your company uses your phone system to call a customer, it is auto-logged in Salesforce. Every email is logged. Every sale, every transaction, every interaction.
Now when "Bob the amazing Sales Guy" leaves you have a central repository of every contact he's made in every company he's worked with on your behalf. This means you build institutional knowledge instead of tribal knowledge.
So now lets say a couple years have gone by, and you want to publish a white paper on pie consumption, so you hand the project off to your research and analytics team. Thanks to Salesforce they have knowledge of every person your company has ever contacted about pies, and therefore have a great jumping off point to start with interviews for the whitepaper.