I definitely used to do this when I was little (I mean, didn't everyone talk to their toys when they were a kid?), and I still find myself doing it now, to a certain extent. If I find one in the wild that's particularly filthy I tend to be like 'Oh yikes, I need to get you home and clean you up, girl'. Usually when I'm cleaning them or styling their hair I mumble little things about the process to them, or comment on something like 'Wow your hair's actually really nice', or 'You don't have any rubs on your symbols, that's awesome'. And if I knock one of my ponies down I apologize to them on instinct.
I don't think I can say I've held full-on conversations with my ponies since I was little but I do sometimes talk at them >u<