News of David Koch's death on Friday drew out many critics of the billionaire industrialist and his equally controversial brother, with some taking to social media to welcome the news.

The LGBT magazine The Advocate tweeted: "Ding Dong #David Koch." Actor Ron Perlman added: "Wishing the Koch brothers a speedy reunion," while progressive activist Ryan Knight tweeted that his death is a "great GAIN for the planet."

Some of this was likely fuelled by the toxicity of U.S. politics right now, says Christopher Leonard, author of Kochland: The Secret History of Koch Industries and Corporate Power in America.

But it's also rooted in some substance, and the degree in which opponents of Koch and his brother Charles resent both their views and the significant impact these billionaires have had on U.S. political life.

"It's a combination of their wealth and their effectiveness," Leonard said. "They really have had a massive effect on U.S. politics.

"But the other part of it is they have been caricatured. They've become a cartoon. They've become a stand-in for everything wrong with American politics. For many people in America they are billionaires who affect policy deeply."

However, there's also no denying, says Leonard, that the brothers have been among the most influential and effective corporate lobbyists for deeply conservative causes over the last 40 years.

"David and Charles Koch have built a political influence network that is really unrivalled in corporate America," he said.

Free market crusaders

There are certainly wealthy liberals who wield their own political power and influence. Billionaire George Soros, for example, is very politically active, runs think-tanks for the left, and donates lots of money to liberal causes.

But Jim Geraghrty, the senior political correspondent of the conservative magazine National Review, wrote that the difference between wealthy liberal activists like Soros and the Koch brothers, is that they are better at achieving their goals and focusing on "the long-term and easily-overlooked corners of the governing process — i.e., state legislatures, local tax initiatives and the political races that aren't 'sexy.'"

And the Koch political machine, says Leonard, dwarfs all others.

"There's no equivalent group like that run by anyone on the left or right. So, taken together, this is a political influence machine that is unrivalled in America," Leonard said.

Their politics have been libertarian — both anti-government, tax-cutting warriors and unapologetic free market crusaders who opposed all kinds of social programs, business and environmental regulations.

David, who lived in New York City, was the Libertarian Party's vice-presidential candidate in 1980. (Lucas Jackson/Reuters)

But while some of those views may find common cause with Republicans, the brothers have differed with many conservatives on social issues — supporting gay rights, being pro-choice on abortion and opposing drug laws.

It was those social views, according to David, that led him to run for the vice-presidency in 1980 under the Libertarian Party banner.

Initially, the brothers stuck to supporting pure libertarian causes and groups, said Brian Doherty, senior editor of the libertarian magazine Reason, and author of Radicals for Capitalism: A History of the Modern American Libertarian Movement.

But at a certain point in the last 15 to 20 years, they decided they would interact with one of America's two major parties. And at least on the economic angle, the Republicans were a better fit.

"They continued to try to push libertarian ideas but they just started trying to do it within a major party context," he said.

'Push libertarian ideas'

But it also meant they would support Republican candidates whose views, at least on some social issues, clashed with their own.

Doherty said the new coziness with the Republicans certainly disgruntled some libertarians. But it also meant that progressives wouldn't cut them slack for their personal socially liberal views.

"David Koch may say he supports marriage equality but every political check he's written says the exact opposite," Advocate executive editor Neal Broverman wrote in 2014.

In 2004, the brothers founded Americans For Prosperity, a conservative/libertarian advocacy group, built through a network of wealthy donors. It became a nationwide network of volunteers and employees that could knock on doors, protest at town hall meetings, drive to Washington and lobby lawmakers.

Members of the American Federation of Teachers hold up signs depicting David Koch and Education Secretary Betsy DeVos while demonstrating in support of unions, in Washington in February 2018. (Jacquelyn Martin/Associated Press)

That money was used to oppose a number of policies favoured by Democrats, including President Barack Obama's health-care plan, proposed gun laws and union and workers' rights. They were also credited for playing in the rise of the conservative Tea Party.

In terms of policy, Leonard believes the brothers were most effective thwarting action on climate change and played a pivotal role in not only delaying but derailing any efforts to regulate greenhouse gas emissions.

He said they gutted the Republican Party of any moderates who might be willing to act on climate change.

"They really had a scorched earth effort to take away any politicians in the Republican Party not just willing to regulate greenhouse gas emissions but to acknowledge the science was real."

At its peak, Americans For Prosperity was raising basically as much money as the Republican National Committee, says Daniel Schulman, author of Sons of Wichita: How the Koch Brothers Became America's Most Powerful and Private Dynasty.

"They had their own data operation that rivalled the Republican Party's data operation. So they basically did establish their own centre of gravity within the Republican Party."

And they have played an "incredibly influential role" in helping conservative opinion makers, influencers and politicians, Schulman said.

"There are a variety of other politicians who if they don't owe their political rise to help from the Kochs they certainly got an assist over the years from them."