So, what you are saying is that any lawyer can work under private firms who assist for immigration-related work of Canada, not the one who is specially dealing with immigration laws. Any private firm assists with such immigration-related issue will always have experienced people in the relevant field they will not keep anyone like this who even don't have any knowledge about the immigration laws of Canada,
Private firms can assist you. Private firms have experts in their company. But they do not have 100% success rate. As each case is unique. In the CAIPS issue, I was merely saying that its not just immgration lawyers who can order those notes. As per link I provided, any Canadian citizen may order that.