Decompile is even easier than rom hacking… since you have the rom source code now…. So you can insert files instead of just replacing or the slightly more work of modifying (which you claimed isn’t possible…?)

Why would you ever work through an emulator?

You’re using an audio book, but it’s actually more an album, you can change the tracks on the cd, but you can’t easily change the song in the middle, but just like an audiobook, you can mute or just delete the content, you’re saying you can’t do anything, this is just wrong on every level. Rom hacks ARE still able to do this though. Although most just replace files with others by changing the whole data.

A rom or iso is just a compilation of files that’s read and interpreted by the emulator or console. Why are you thinking it’s a singular file like an audio book? It’s more of a .zip file.