Death has his problems but u cannot say that Nurgle does need nothing.
They have allegiance abilities but not traits or artefacts. They have low sinergy, the command ability of the guo is a joke, they pack 5 named characters, their only option is blightkings for maintaing rotbringers allegiance, daemons cannot ally with rotbringers...
The new allegiance imho is just completely unplayable without traits, i will continue to play with regular chaos. And btw Nurgle is the only chaos god stick in this situation.
Death has his problems but you cannot say that other factions have their too. Death, gutbuster, Nurgle, verminus, aelfs... They are all in the same boat.
Oh and btw the guo has 1 year less than me (21), one of the older miniatures still Alive in the sentire GW range.
Just my 2 cents as a only Nurgle player.