The game uses archive files to package the game files and if one file changes then that breaks all the mods, and since there are several key files it essentially breaks that entire category of mod. So they aren't as crazy as they sound even if you are correct.
If applying a patch extracts and repacks the archive, then unrelated files can definitely be changed. See for example Minecraft jarmodding, which is just merging two zips.
The game uses archive files to package the game files and if one file changes then that breaks all the mods, and since there are several key files it essentially breaks that entire category of mod. So they aren't as crazy as they sound even if you are correct.
If applying a patch extracts and repacks the archive, then unrelated files can definitely be changed. See for example Minecraft jarmodding, which is just merging two zips.