Having children is absolutely a valuable experience! We definitely have coaches who have several children. I think this can cut both ways, though. I was a child psychologist before I had my own children. I don't think it dramatically changed the way I support parents. Mostly because I wasn't working from the framework of my personal experience. What I do with my own children is irrelevant when helping a parent (this is the difference between advice and evidence-based information) - and in fact, there is nothing worse than a therapist saying 'well, with MY kids at every turn (it can be helpful, but you have to be careful)....' Having a child gives you lots of experience, but it doesn't make you an expert in child development (it does help when working with parents, and a LOT of parents appreciate when our coaches have several kids of their own). Also, there are often many ways to get to a goal, and it varies by the child, parent and family. Professionals can often speak to a range of choices (think: sleep) rather than just their own personal experience.
I should also say that we have parents on our service who have 5 children, and tell us each is different, and they still appreciate the support and wisdom.
Child development industry fads come and go, sometimes drifting away from sanity and reality.