> This glitch can permanently ruin a game file and, in the extreme case, possibly even erase or damage your cartridge. How can this glitch erase the ROM in a cartridge?
I doubt it's implying that. It's maybe possible that you could glitch the save data in a way that the game would crash or misbehave just from trying to read it, though, with no way to fix it short of discharging the save data somehow (I don't recall if gameboy games used battery backup or some kind of flash).
Exactly. Most console games tend to treat saved game data as non-hostile, because they assume that only their own code will write it; buggy loaders that crash on corrupted data are not uncommon. (This has changed with more recent consoles, after multiple cases of saved game exploits used for jailbreaking; see, for instance, http://wiibrew.org/wiki/Category:Homebrew_exploits .) Memory-corruption bugs in games can overwrite saved games in ways that lead to such issues.