We all know the research about groupthink. Unfortunately, if people's voices are not represented in a parliament, policy isn't of the same quality.
Take the example of domestic violence. In most countries it used to be considered a private matter. If you called the police out to it, they would not deal with. Then when you actually get women entering politics, suddenly it's a public policy issue. It's very similar with child care.
That can be spread across different groups. You need to have people's voices in parliament in order to deliver better policy for their communities.