What are the disadvantages of applying for a Canadian green card as a refugee?

Refugees are a kind of Canadian green card, called protective green card. Among Canadian refugees, China people have the highest refusal rate, up to 60%. After obtaining refugees, the green card has a special mark and cannot go back to China to visit relatives. If the refugee green card meets the Canadian conditions, he can become a Canadian citizen and finally get a Canadian passport. There is no way for refugees to turn into regular green cards in Canada.