Those discs aren't going to do you much good if you don't have access to or have had access to PSN, since most games ship with a huge day 1 patch to fix all the issues between going gold and the date of sale.

Movies/Music/Books can be displayed and played back on damn near anything. Games, especially modern games, exist in both a variable state (constantly revised/updated), but also with a much more limited ability to access the content.

I lost a small number of games due to PlayStation support not being able to get around the fact that although I purchased some of them via PayPal, I also bought other games with a credit card. They could verify I owned the actual account and I answered all security questions but they still wouldn't fix whatever issue I had (this was at least 5 years ago so I forget particulars).

That experience forever turned me off to relying on digital-only.

To your points, having a PSN account is necessary but I can always create a new one if need be.

Whenever possible, I prioritize non-DRM media for purchase.

... You can't store MP3 files why? You're renting your hard drives, too?

I meant digital purchases with DRM or inside a digital store like Vudu or Amazon Prime.