I have, but I'm really hesitant to. The main reason being that if the system I invest in one day goes away then I'd have to rebuilt my catalog elsewhere. Online services can disappear just like that. I mentioned Filmogs in my first post, a sister site of Discogs that focused on films. Good thing I didn't start building my collection there because it's gone now. Even an app that you download isn't guaranteed to last forever. Perhaps it will be abandoned and not work on a future OS. In the case of Eric's Movie Database, it relies on Internet Explorer to grab the info from online databases. I know MS is keeping IE in Win10 for compatibility, but how much longer do we expect that to last? So if IE disappears from the OS and Eric no longer updates his app, then you're screwed.
In contrast to that, I'll always be able to use an Excel spreadsheet. And there's a number of things I can do with it. I can upload it to my Office 365 cloud and access it anywhere, or Google docs and check it on my phone. I can export to CSV or TXT and then import it to any number of things in the future. It's pretty much future-proof. And Excel is powerful enough that I can get what I want out of it, feature-wise.