There’s an outdated rule in English that states you shouldn’t end a sentence with a preposition. It dates back to a time when writers applied Latin’s grammatical rules to English. It’s mostly ignored now.

But... it's a title, not a sentence. Many book titles are even a single word, which is even less a sentence. Why would a grammatical convention for sentences apply to book titles?

Heck if I know. All I know is I am a lot more worked up about the misuse of “less” when the correct word is “fewer”.

Whom would care fewer?

Which itself was simply the preference of a spinster who wrote a grammar book.

English has no rules like that, only preferences.