I don't know about baby therapy.
Many of us on here have found doll therapy very good, maybe this is what they mean? but are putting it in a term they feel will be more acceptable.
I didn't use dolls for my mum instead I bought mum soft teddies, she adored them, seemed to think they were her real baby.
She cuddled, played and whispered to it . When mum could no longer do these things, we ensured it was snuggled into her neck.
It brought mum great comfort.