It doesn't matter how long ago a psychiatric history was or if there's been no further contact, that can in itself alone be a reason for removing a child
That part isn't true. No court would make orders for a child based on the parent having a long ago psychiatric history or having been a victim of abuse, if that parent is stable and able to parent in a good enough way now. Those previous issues may be considered as part of the picture where the parent is not able to parent because of other things, or may lead to the parent coming under more scrutiny than someone else might, but they are not the sole reason a child would be removed.
there doesn't have to be any allegations of cruelty or neglect.
Yes there does, even if that is a fear of future neglect or harm based on previous actions for the parent eg with older children. I know of a woman who had her child removed at birth because she wouldn't leave the paedophile father who had already sexually abused all of her older children. Should we just wait for that baby to be abused first?
Sometimes babies are taken shortly after delivery and the mother has been told it will happen and has to give birth knowing her child will be taken from her.
Yes, for instance where the mother has had multiple previous children removed because of neglect or abuse and hasn't made any changes that would lead anyone to believe anything different would be the fate of this baby, as above.
Please don't scare people who may be reading this thread and need help and support, into fearing that their child will be removed for no reason if they come to the attention of the authorities. That could leave vulnerable children who could be protected and families who are struggling, in greater danger.
Is the system perfect? No. But there is a high bar for a parent to lose their child and it's not done lightly.