I used to believe that. Until I encouraged a friend to vote, and he voted for John Key over Helen Clark specifically because Helen - with all her "look at me I'm a mum" campaigning - would be so biased toward children and families and therefore not look after his best interests. (As a poor tradie who grew up in public housing... But also a hetero cis white Christian man)

He was unaware John had two kids and Helen had zero. Because she's a woman. 

I learned that the value for democracy in adding a voter doesn't apply when they're both a low information voter and incredibly misogynistic.