I think that's a massive oversimplification, an attempt to take the Big Man theory of history and stretching it over the whole populace. There are absolutely Big Men in history, but if you ask me, what makes them big is that they invented. Napoleon, Genghis Khan, huge catalysts for invention and social reform. Rome grew great because Scipio and others looked at what Hannibal did and learned from it, and revolutionized warfare as a result. Inventions give countries advantages. Inventions in material use, in resource gathering (mining, agriculture, metallurgy etc.), in economy, social fabric, politics, military organization and many other things. But it's hard as hell to stay ahead of the invention curve for centuries. After you've invented something which gives you an advantage, others will start looking to catch up, and they can look at what you've already invented, and one good idea doesn't automatically lead to other similarly good ideas. Rome invented new ways of fighting, new ways of organizing society, new ways of politics, and it gave them an edge. As time went by, these advantages let them conquer others. As time kept going by, many things changed inside their borders, and outside their borders. Their enemies grew more advanced, and Rome itself struggled to come up with enough new inventions to let them gain the upper hand again. Then outside circumstances happened, with huge ethnic immigrations from outside their borders. Rome couldn't handle it, but I don't think Rome could ever have handled it. If it had happened two centuries earlier, I bet the result would've been the same.
Similarly with 20th century England, circumstances were very different from the 19th century. I don't think the 19th century British would've done much better solving the 20th century problems. Even Napoleon grew tired and outdated and eventually lost, as he failed to stay ahead of the curve he himself had once spearheaded.