Well, I played in a totally vanilla game and after 3 days, the game deleted about half of the sims that I put in - I had a total population of 667 (in houses and not in world) and only 1 sim protected in my households. The sims in houses were left alone but after deleting all those sims that had npc jobs assigned the game still generated 19 train wrecks to take their place.
I see now why so many rely on the no culling feature of mods. All that work to download and place them in world and they were gone within 3 sim days. So sad.