Comment by ben_w

It requires imperfect reproduction where the imperfections alter the probability of further reproduction.

If each black hole in our universe contained a pocket universe with very slightly different laws of physics (to each other and to us), but the same amount of mass-energy on the inside as our universe had when it started, then (1) those pocket universes able to create stars and black holes would also go on to create black holes with pocket universes, but also (2) those pocket universes not able to create black holes, would not create more pocket universes.

I have never seen a reason to think that this could happen, nor why such pocket universes might have more mass on the inside than they appear to have on the outside, but that's the argument.