Yes, we have developed the capabilities to mass destruct, but then we have always used wars to improve on whatever the war technology is at the time. Over time we become more efficient at it. The Industrial Revolution just means we can do it faster now than we used to. Is that capitalism, or is that human desire to defeat the enemy?
There have always been wars throughout history. And yes, there are countless wars today. I would submit, however, that there may be fewer wars in number today than in the past because, with the advances gained from capitalism, countries fear they'll lose what they do have.