What is Canada's unlimited acceptance of refugees and immigrants for?

First of all, it is not "unlimited reception". Immigration Canada announces the planned immigration and refugee quotas every year. In fact, the number of immigrants and refugees admitted each year is almost the same as this quota.

Canada itself is a country founded by immigrants. Canadians are immigrants or descendants of immigrants except a few Indians (called "First Nations" in Canada), Inuit and other indigenous peoples. In addition, Canada has a small population and a lack of labor. Therefore, the introduction of immigrants is a "national policy" that Canada has long adhered to.