When adults talk to children, they use a lot of diminutives. When they talk to other adults, they use diminutives much less often. When they talk to pets, regardless of their age, they use plenty of diminutives. Why?
In my thesis , the use of diminutives was associated with closeness to the addressee. You do not expect people to use them with people they do not know. Thus, they are used more with close people such as friends and family. As for animals, there is the sense they are little and that can explain their use. The problem with diminutives , they are discourse markers which their use and meaning can differ from one user to another.
well , we can assume that. After all, the primary use of diminutives is to mean little. It would be weird to find someone referring to a lion by diminutives.