Joseph Stalin I understand now. Another consequence of canonizing glorified fan fiction, it appears. Imoen gives up her essence if you take her to the throne. She would also be dead by BG3 if you didn't take her, though she could have had a kid I suppose. Her children would be diluted, if we take a traditional view of heredity. Sarevok no longer had any essence after PC killed him, even after being resurrected. Saradush doesn't really have survivors other than (potentially) Viekang. The city gets razed and butchered by Yaga Shura's army. Still, it's fine to assume that not
every Bhaalspawn ended up in Saradush. It seems like a really dumb oversight.