We do have many many topics for babies and toddlers but they have been broken down because they were so popular.
I would hazard a guess that we started out with a Babies topic but it had so many posts about the many scary questions having a small child raises that we broke it down into various different baby related topics.
i think that originally we just had "parenting" and then the parents of teens and pre-teens asked for a separate section because most of the people posting in parenting had babies and young children... so that's kind of the default place to post iyswim?
I agree with scaryfairy28 I think an under 2 for example section would be a good idea. I always think of parenting as something a bit different, maybe linked to behaviour etc. For example I am currently looking for a bit of advice re nappy rash, I know there's childrens health but I think a specific age band topic would be useful. The postnatal clubs are good for advice but obviously the amount of posters is quite limited.