One important part of a liberal democratic system like Canada’s is that the government must be answerable to the people. Another important aspect of liberalism is that the people should have the freedom to express their opinions. Both of these aspects of democracy are enhanced (at least ideally) by Question Period.
Question Period allows the people, through their representatives, to express their opinions and to push the government when it acts in ways that the people do not like. At each Question Period, members of opposition parties have the chance to challenge members of the governing party. They can ask questions that convey to the government what actions (or inactions) of the government are unacceptable to the opposition. By doing so, they force the government to at least hear their objections to government policy. This also helps to force the government to answer to the people through their representatives.
Of course, Question Period does not guarantee that the government will actually act on any of the opposition’s concerns. However, it does advance democracy by giving the opposition a formal and guaranteed forum in which to express their concerns and to hold government accountable.