As someone mentioned, statistically, care leavers have poorer outcomes in a number of important areas e.g. health. It makes sense to ensure that people who have left care are therefore given enough support as they may not have received it in childhood.
You are so right, wayfaying. However, it is just so very difficult for the parents to accept help and support from the very agencies they associate with the worse times in their lives. And however much they know intellectually that the agencies had done the right thing, emotionally there will always be an instinctive anger against them.
For instance one young man I am looking after at the moment (mid teens) is a delight. Clever, funny, kind, has a wonderful fun personality and a strong desire to do well at school and university. He has dealt with his past as well as any child I have fostered. Yet when his social worker visits, a lady who has done a great deal for him, he becomes sullen and angry. He knows he is this way, but it is is instinctive. Something in his subconscious is triggered whenever anyone else from children's services has any contact with him. So for the OP, and other young parents, I do understand how difficult it can be to work with the agencies that feel like the enemy. Though those that succeed the most are those who bite their lip and accept the help as graciously as possible.
Again, I wish you luck OP. Are you in contact with any past foster carers? I am always so pleased to help and support the young people I have fostered, when they reach adulthood. (Well, not everyone, I'm not a saint!!).