Understood, but there's only so much the conquistadors can do even with gunpowder. Guns can do a lot of damage against bronze swords and armor, but if they have more soldiers than you have bullets, then you'll still lose.

Of course, if the conquistadors could build a modern tank, they'd be virtually invincible. But in order to do that, they'd need to smelt steel, vulcanize rubber, refine petroleum, manufacture electronics, etc. Even if they had perfect knowledge of these technologies, they couldn't duplicate them in ye olde Aztec times, because such technologies require a large portion of the world's population to be up to speed. There's a limit to how much you can do armed with nothing but a pocket knife and a volcano.

I think this was XiXiDu's point: knowledge alone is not enough, you also need to put in a lot of work (which is often measured in centuries) in order to apply it.