Isn't writing an article like this just daring someone to make the system in question more cursed, more likely to produce errors, harder to reason about, etc.? In the same spirit as, "well technically this common assumption about C behavior is undefined, so let's add some nasal demons to save 2 us (and make me look clever)"?
Am I missing something or is this just evil? I guess I'm taking it too seriously.
Not really, you should understand the limitations of the system you are working with, including expected limitations that don't actually exist or only exist for some parts.
For example, knowing that inodes 0 are technically possible will tell you to not rely on inode 0 as a special magic number. It's when parts of the system disagree about details like this that you get issues, not when you learn about them.