Much like Twitter, Reddit is a tremendously powerful social phenomenon, one that can produce things of real and lasting value, and one that brings people together around shared interests and passions. But both are also massive honey pots for trolls and grief-artists.

The challenge for both is: Can they somehow keep the good things, while also making the horrible things a little harder? Is there a way to enable users with positive intentions and still disable those who just want to watch the world burn?

Reddit is confronting those questions again after CEO Steve Huffman admitted to altering comments made by users, a flagrant violation of some of the core principles of the community. And Huffman knows those principles well, because in addition to being CEO, he is a co-founder of the site, which he and Alexis Ohanian started in 2005.

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Huffman said he edited comments that were posted by users because a large number of them were abusive, alleging that he was a pedophile, and mentioned him by name (or rather, by his Reddit handle, which is “spez”). He changed them so that they mentioned moderators of the forum instead.

“I am sorry for compromising the trust you all have in Reddit,” Huffman said in a post on Wednesday. “It is heartbreaking to think that my actions distracted people from their family over the holiday; instigated harassment of our moderators; and may have harmed Reddit itself, which I love more than just about anything.”

In typical Reddit fashion, the abuse began because the site shut down a popular forum (or sub-Reddit) known as Pizzagate, which was discussing a conspiracy theory about how Bill and Hillary Clinton were allegedly involved in a pedophile ring. Users took to a popular forum about Donald Trump and started posting the abusive comments about Huffman.

“As much as we try to maintain a good relationship with you all, it does get old getting called a pedophile constantly,” Huffman said in a post after the incident. “As the CEO, I shouldn’t play such games, and it’s all fixed now. I most assuredly won’t do this again.”

Over the years, Reddit has become known for empowering remarkable acts of kindness—including sending pizza to a young girl on a cancer ward—but also hugely offensive acts of abuse, including entire forums devoted to harassing women, talking about the inferiority of black people, and other offensive material.

Reddit has been trying to control this kind of behavior for some time by banning sub-Reddits about various topics and removing moderators (who are volunteers, and are nominated by users).

But much like Twitter, which is routinely criticized for not doing more to stop harassment of women and people of color on the service, Reddit can’t seem to do enough—and what it does do is often criticized by those who argue it is betraying its free speech principles and caving in to political correctness. It’s the classic rock-and-a-hard-place dilemma.

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Twitter has fiddled with the mute function to make it easier for those who have been harassed to ignore their abusers, but many argue that this is too little and too late. Reddit has tried to empower moderators, but some say those moves are also insufficient to solve the problem.

The company said it is stepping up its efforts by taking action against some of its “most toxic users,” ranging from warnings and time-out periods to permanent bans. Huffman said the site will also continue to “take privileges from communities whose users continually cross the line.”

The challenges facing both Twitter and Reddit have become even more acute as both companies have come under increased financial pressure. Twitter (TWTR) is trying hard to justify its $13 billion market value, while Reddit is trying to justify the $50 million in funding it raised in 2014, which gave the company a theoretical value of about $500 million.

In Twitter’s case, the toxic nature of some of the behavior on the network has caused problems in reaching that goal. Two of the companies that were reportedly considering an acquisition of the company said that trolls and abuse were one of the reasons they declined to pursue a bid.

Reddit has said that advertisers are interested in using its service to reach new potential customers or fans, and the site has done a number of experiments with brands like Coca-Cola. But it’s not hard to imagine that some of the abusive content on Reddit has kept at least some potential advertisers from doing more.

The risk for both companies—Reddit and Twitter—is that by cracking down on abuse, they also squeeze the life out of their services, and thus wind up with fewer users and less engagement, making it even more difficult to reach their financial goals. And yet, not taking action isn’t really an option either.