One of the worst issues with preserving and archiving old ISOs obtained from internet is the format salad.

Everybody says "Why do you even need an optical drive emulator, you can mount ISO files on Windows 10".
But most of the stuff was made in a time when you needed to replicate #anticopy measures. So you have images made with #nero, #Discjuggler, #CloneCD, #Alcohol120%, Blindwrite... And Suddenly the only program that can still open them is #DaemonTools, which is not exactly safe software.