Yogg-Saron gave the Curse of Flesh and as for ties between the Old God N’Zoth and Death: The Chronicle specifically states that Old Gods in general live only to transform places they infest into places of Death and Despair.
The Chronicle also states that Void Lords are Dark Spirits in the Void. Furthermore the Chronicle never states that the Void Lords rule the Void just that they are the Old Gods’ masters.
The Twilight’s Hammer also states that Death is a gift in Darkshore after the Night Warrior Questline. The Old Gods and the Void Lords are indeed as tied to Death as they are to the Void.
The main problem is probably beings aligned only with the Void or only with Death…