If we were to give every nation an upgrade , only they have access to, then the calls of bias would get louder depending on the latest meta.
I've always thought we should be fighting over the best materials ( carta when it was sought after seemed to work well ) and If all the upgrade mats were available at conquerable ports, then why not stop upgrades being smuggled around in a magic box and perhaps only have books hidden away
A nation having a ship of its own would cause issues also. everything capturable, by everyone able to do so IMHO works best