Teams full of similar people underperform. While sameness can create cohesion, cookie-cutter teams can’t successfully compete with diverse teams that can draw on a broad range of talents, perspectives and insights. At least that’s what empirical data from lefty organisations including McKinsey, Credit Suisse and the IMF have to say.

But facts have a well-known leftwing bias, so maybe a sporting analogy will help. The Men’s Rugby World Cup is now being played in Japan. Being a men’s competition, the teams are comprised solely of blokes, but there is still an incredible diversity in the physical and performance attributes of players involved. The tallest player, Rory Arnold, is 6 foot 10 inches while the shortest player, Fumiaki Tanaka of Japan, is 5 foot 5 inches. Some players have more than a decade of representative experience, while others are new to the World Cup. Some are fast, some are strong, some can really kick and some can really jump. The only thing that can be said for certain is that the team that wins the Rugby World Cup will not be full of clones of the “ideal player”.

There are lots of reasons why our parliaments, our company boards and our media feed should be as diverse as the communities that we live in. The main one is fairness. Most Australians aren’t white men between 50 and 70 years old (though I almost am!) but many of our most important institutions are chock full of men who fit that bill. Indeed, there are more men named John who run big companies in Australia than there are women. And more men named Peter. And David.

Given that there is no evidence that men or Caucasians are more intelligent, creative or strategic than women or people of other races, it is inconceivable that the current gender and racial distribution of powerful positions is based on merit. Fairness alone requires this problem to be fixed.

And then there is performance. Lest I invite the full fury of the rightwing commentariat for talking beyond my expertise, it’s probably best that I simply quote the virtue signallers from the International Monetary Fund who concluded that: “Our analysis springs from the observation – supported by considerable microeconomic evidence – that women and men bring different skills and perspectives to the workplace, including different attitudes to risk and collaboration. Studies have also shown that the financial performance of firms improves with more gender-equal corporate boards.”

Achieving diversity among our leaders isn’t a purely progressive objective. Even Scott Morrison agrees, in principle, that his party needs to recruit more women into parliament. But, much like his “in-principle” commitment to reduce greenhouse gas emissions, he simply hasn’t been able to achieve much progress on gender equity yet.

The main reason that we need diversity in our leaders is that our leaders are more than the sum of the decisions they make on our behalf. Leaders, via their behaviour and their identity, say something important about the organisations they represent, and about our society.

Which brings me to Greta Thunberg. There is no doubt that older white men have a dominant voice in the Australian media landscape. And there is also no doubt that some of the loudest of those white male voices expressed the most outrage that a young woman was given a global platform on which to speak.

Much has been written about why so many old conservative men felt so angry that a young woman would speak truth to power. But what sticks out for me is that the Australian men who raged the loudest claim to do exactly what Thunberg dared to do. You’d think they would at least applaud her chutzpah.

The world – and even Australia – is gradually changing, even if the loudest voices are not

Alan Jones doesn’t let titles like premier or prime minister stop him tearing shreds off guests who are brave enough to come on his show but are not “good enough” to meet the standards he sets for them.

Likewise, Andrew Bolt. Whether it was the Liberal prime minister Malcolm Turnbull or the Labor prime minister Julia Gillard, Bolt has felt free to let the world know whenever a politician or business leader doesn’t live up to his expectations.

But how dare a young woman hold elected leaders to the same account. How dare a “child”, a “brat”, a mere “girl” have the same sense of entitlement to express her judgment as the old codgers?

A former AFL player called Sam Newman asked: “WHO lets this shit have a platform? Mendacious, inbred sycophants, that’s who. #ClimateChangeHoax.”

Who indeed. Maybe the 500,000 people who turned up at the march she led in Montreal? Maybe the 300,000 Australians who followed her lead and joined the climate strike last month?

But let’s flip the question. Who gives former football players a loud voice in debates about climate change? Who gives Alan Jones the right to use violent language against female politicians? You guessed it, the boards and chief executives – who are overwhelmingly male.

If corporate boards in Australia had a majority of young women setting organisational strategy and culture, it is hard to believe that men who repeatedly incite violence against women would remain on air. Similarly, it’s hard to believe that climate denial would be as common on boards dominated by younger people as it is in Australia today.

Leaders matter. As former army chief Lieutenant General David Morrison once said: “The standard you walk past is the standard you accept.” For decades, Australian parliaments and corporate boards have accepted climate denial, racism, sexism and even violence against women as “the price we pay to live in a free country” or even “just the way people are”.

But the world – and Australia – is gradually changing, even if the loudest voices are not. It took 119 years to overturn the New South Wales law against abortion and, when it finally happened, conservative Coalition MPs complained that the process was “rushed”. Similarly, it was conservative Coalition MPs who thought we “rushed” the equal marriage decision too. And, unsurprisingly, it’s the same group of people who believe we shouldn’t “rush” into reducing greenhouse gas emissions either.

One of the most important roles our leaders play is to decide which problems are urgent and which can wait. Scott Morrison’s Coalition wants to prevent the use of the term “almond milk” and inquire into discrimination against men in the family courts. Greta Thunberg thinks we should stop building new coalmines and urgently increase investment in renewable energy. But who is she to say what’s important and what’s not? Doesn’t she know? We have parliaments, boards and a media full of older men to tell us what’s important.

That’s why diversity really matters.

• Richard Denniss is the chief economist at the Australia Institute