answer:I want to say that there are some screw-based ones, but I’ve been looking for an illustration and haven’t found one yet. I think I have seen such an illustration or even an actual one in a museum, and I think it’s what this fellow describes here as a ‘screw and handle’ crossbow . I’ll keep looking. I (also) think it can be done, but would my intuition says it may be more expensive / difficult to build than other designs, and I think it would likely trade off potential pull with speed, but potential pull may generally have been limited by other factors to a maximum that was as attainable by other mechanisms, so my guess is that for some combination of those factors, it wasn’t often done. I’d expect if it were more efficient, we’d see more of them, and they’re rare enough I’m finding none so far.