One is a requirement to be an organism. The other is a nice to have. A great many creatures simply die after reproducing, for example, which we can interpret to mean the minimum requirement has been met and anything beyond that isn't as important, if we like to view it that way.

Forming that small person is also a bit of a chaotic and messy process involving chance errors of various kinds and variations in the way parts grew. In a sense, the person formed would never be exactly the same if you tried again with the same inputs either.

That this system works as well as it does is a miracle.

EDIT: Missing words.