Well sure, but that is a bit of a simplistic take on the matter. If you could trust in the goodness and decency of external actors, or if all of humanity was s

Well sure, but that is a bit of a simplistic take on the matter. If you could trust in the goodness and decency of external actors, or if all of humanity was super-rational, then there would be no need for nationalism or perhaps even nation states. But humanity is not super rational, politicians will use sentiments including nationalism to gain power, and just wishing it away will not make it so that all humans suddenly become trustworthy or super rational, thus the need for nationalism and nation states to bring about a hopefully stable balance of power.