concept is fine, but after concept comes the need for doctrine change, manufacture retooling, chemical/metallurgical advancement and pretty much everything that comes with scale. And pre-industrial revolution, that just wasn't possible. It moved real quick once it did though

Think of it another way. We know we can make fuck you space lasers zap zap right now. We know the concept and the way to do it. But other related engineering and sciences aren't there yet.