For me it was just killing off my Townies too much, and while I was fine losing some of the older ones I've had in my saves for a long time, it got excessive and I shut it off.
I only had pet and child adoption, plus having a baby turned on for a few Townie families (most of my Townies are single Sims) and I never saw any traction with it, but my understanding is that's affected by traits. I'm guessing the Sims I was allowing it for didn't have the right traits.
I boot out nearly all the premade Sims too when I start a new save, so I don't have a lot of unplayed households living on lots either. And I had it turned off on the ones I kept, because I'll want to play them at some point.
