Sure, you can come up with an algorithm question hard and obscure enough that no one will be able to answer it in the time given and no one will have bothered t

Sure, you can come up with an algorithm question hard and obscure enough that no one will be able to answer it in the time given and no one will have bothered to memorize it because it's so obscure. That doesn't mean all "implement X algorithm questions" are categorically bad.