Many classical algorithms were discovered before we had access to classical computers, but that's because we were doing classical computing by hand, and that ma

Many classical algorithms were discovered before we had access to classical computers, but that's because we were doing classical computing by hand, and that made them useful and thus people looked out for them. Quantum computers are different, because we have reason to think that they can scale exponentially faster than "follow these steps on pen and paper, but more faster", unlike classical computers.