Big Tech has received its share of criticism in recent years, but in a new interview, venture capitalist and tech critic Roger McNamee specifically singled out Facebook (FB) and Google (GOOG, GOOGL) for their roles in spreading disinformation.

Why is it so important to address these companies?

“Because they’re the reason we can’t fix climate change,” McNamee, author of the book "Zucked: Waking Up to the Facebook Catastrophe,” said this week on The Final Round. “They’re the reason why we have an epidemic of measles due to the anti-vaxers. They’re the reason why white supremacy and gun violence are on the rise because they empower the most disaffected people in society, and they give them a disproportionate political voice.”

Vaccine misinformation is prevalent on the internet, although many social media companies including Facebook and Pinterest (PINS) have made efforts to curb the spread of it. When users search for content on vaccines, Facebook and Instagram will direct those individuals to the CDC if they’re in the United States, or the World Health Organization in other parts of the world. This is to ensure the information they’re receiving is coming from legitimate medical sources.

However, BuzzFeed reported just last month that Facebook was still allowing anti-vax ads on its platform.

Facebook responded to the controversy by stating to BuzzFeed: “Facebook does not have a policy that bans advertising on the basis that it expresses opposition to vaccines. Our policy is to ban ads containing vaccine misinformation.”

‘Job one right now is to deal with these guys’

In January 2019, Mother Jones reported that Google, Facebook, and Microsoft (MSFT) — all companies that have acknowledged the dangers of global warming — sponsored a conference that promoted the denial of climate change.

Meanwhile, videos propagating climate change denial have proliferated on Google-owned YouTube. A study over the summer analyzed 200 videos about climate change on YouTube and found that 91 of them promoted conspiracy theories about climate engineering and climate change. A spokesperson for YouTube told Time Magazine this month that its systems “surface information panels on topics prone to misinformation — including climate change.”

As for McNamee’s comments about white supremacy, it’s true that both Facebook and YouTube have been used by white supremacists to spread their views. Facebook was even used to organize a notorious white supremacist event in Charlottesville, Virginia, that turned deadly in 2017 before the site said it would block white supremacist posts. YouTube also announced over the summer that it was banning white supremacist content.