I constantly hear/see people saying 'Oh all babies are fine being left with anyone as long as they're warm and fed until about 6 months' etc. I have never found this.
Even as a premature baby in nicu , EDs heart monitor would raise when someone else held her, once home she would cry if put down or handed to someone else from day 1. After about 2 months home, she would go for cuddles for a few minutes, then become inconsolable, and now at 9 months, she will go down for longer periods, and sit by other people, but if anyone she doesn't know well picks her up she will scream.
I just don't understand the assumption that babies are clueless about their parents until they're older. And I especially don't understand the 'You're being PFB if you don't leave DC to be babysat as they will be fine' type comments.