One could easily find any number of beings more formidable, overall, than a griffin. The Leviathan wouldn’t notice even the largest of their kind unless, perhaps, she managed to get one of them tangled in two or three of her more important rows of teeth. Likewise, in an actual fight, the tiniest runt of a Dragon could roast an adversarial lion-eagle before the latter could get in more than a few disgruntled snarls and maybe maybe one far-too-far-away swipe of the claws.
But it’s hard to find a guardian more tenacious, more ill-tempered, more steadfast, or more dedicated. You could borrow a Sphynx or two, perhaps, if you could find or create one of that fabulously rare breed. They’re already stone, and long-lasting, and if anyone’s ever bested one of ’em in combat, it’s gone unrecorded in any reputable history.
You could. One oughtn’t, though. Not if what one’s protecting is of really incalculable and irreplaceable value. Because Sphynxes will have their riddles. And riddles can be solved, or circumvented, or otherwise fuddled.
Long experience had taught the Unilluminati that what counted best, at end of day, was having protectors who were really devoted to being wrathful, permanently displeased, forever irritable, and unspeakably territorial. Ergo: Griffins.
It helps to put them somewhere at the end of a vast physical, mental, and metaphysical maze; if sufficiently hard-to-find, well-made, and sturdy, such things have a tendency to weed out many of the more directly troubling challenges. For example, sufficiently frustrating spatial muddles are very good at taking care of outrageous force. You can’t get an army to go through one; the logistics are simply far too complicated to make it anything near worthwhile. Those aforementioned Dragons would never fit, and, at any rate, would certainly never leave the comfort of their treasure-hordes to attempt to plough through a multifaceted geological-psychological labyrinth; and this is equally true of just about any other species with overwhelming magick and/or might on its side).
And no matter what or who you might be, nobody’s keen on ending an exhausting quest at a wild, ugly place whose chief exports are Griffinly annoyance, withering Griffin stares, and the malfeasance of nature which is a Griffin’s truly awful breath. If one has spent sufficient time breeding the beasts, there will be more than enough Griffins to make even the most intrepid of explorers give up, especially if one has been thoughtful enough to leave a large teleportation portal right next to the Maze’s exit.
That’s why it’s Griffins which protect the Nonexistent Library.
And that’s why today, the tribe of Griffins is, down to the very last creature, purple with rage. Because today, someone stole a book.
It’s not the End of the World.
Because you’re not that lucky.