Personally, I started using it 12 or 13 years ago when it was new. I don't remember at what point I realized that I could use it as a place to store, search and retrieve all my piles of paper that needed to be filed or shredded or just tossed.
Using import folders, it became really easy to go through a stack of mail (a week's worth, a month's worth, or many month's worth) and by setting up a folder structure locally and using naming rules in my scanner software (I've gone through a few scanners since starting) I could easily "process" my mail and shred it knowing that if I needed it later I could find it relatively easily.
At some point EN was "hacked" so I moved the stuff that worried me to a local only store.
Now my workflow is broken. v10 made the process much more cumbersome, legacy restored the simplicity.
I don't want to be too long winded, but that's my story. I'm happy to go on if I haven't satisfied your curiosity ...