I don't know why really, it's just 14lb, why does the US/Canada just stick with very large numbers of pounds instead of breaking it up as with others?

Kilograms seem more and more common for human weight too though, largely driven by fitness apps & communities I think. I doubt children in school today are accustomed to stone; only pounds and ounces for birth weight perhaps, but even that is metric medically and converted for the parents' familiarity these days I believe.