I like DVDs because they are read-only and that's security for me. I don't see any USB drives that can be switched into a "read-only" mode at the physical-level like we used to do with the old 3.5" floppies.
I've backed-up all my games & patches & mods (& no-cd cracks, for games that I own legit disks for) on a USB-HDD, but I'd be careful to plug it into a Win-10 PC, lest MS Defender delete some of my .exe files against my will.
I used to burn mainly my patches / mods folders onto DVDs, and wasn't much worried about the actual games that were in disk image files. Now I hear that Win-10 may also scan inside ISO files. Maybe now I'll have to zip them in password-protected archives.
Problem 1: BR discs and drives are much more expensive than DVDs or even USB-HDDs.
Problem 2: They aren't easily available. Optical media has become so niche that I couldn't find a new one to buy anywhere in the local markets, and would have to order one online from far away at higher prices than just buying a used old PC that has a throwaway DVD-RW drive in it.