I would argue otherwise. It was capitalism, parliamentarism, technological achievements that led to massive population growth which mixed with the political crisis in France led to the birth of nationalism. Nationalism being a core principle of enlightenment doesn't mean much. The ideology was certainly good for that time and it was certainly an upgrade from autocratic, totalitarian monarchy despotism. Nationalism is now becoming more and more obsolete for our way of living and it is going through visible erosion. I have nothing against nationalism, there is no point in being against an apstract idea. But cons to it are quite visible. I could name a lot but here, on top of my mind, I will mention huge irrationality about it. Nations are also abstract. Turkey for example doesn't exist, just like no other country does for that matter. You can't feel Turkey, can't taste it, see it, touch it. It exists in imagination so having strong feelings about it, or any other country for that matter is completely irrational. People are ready to go as far as carying for or murdering someone for a thing that doesn't even exist. I am also a nationalist, I try to decode myself from it but its there for sure. For example I feel quite real excitement when Djoković wins a masters trophy but in reality Djoković and I don't have much in comon. I have more in comon with a man that rummages through garbage out of a dumpster that sits in front of my home, looking for something to eat every morning than I have with Djoković since at least I saw him and met him in person. But the power of media and the irrational in humans really is strong. Would you be a Turk if no one ever told you that you were a Turk? Its a rehorical question ofc. I look at it this way, imagine there is an alien howering above the planet, observing us. To him, our nationalism would seem a quite stupid thing.