Partly, these are self-preservation instincts kicking in — no company wants to end up like Reddit, which has struggled to shake its reputation as a den of toxicity — but it is also indicative of an emerging consensus around the moral responsibilities of tech platforms.

Discord allows users to form private, invitation-only chat groups invisible to those outside the app, and it allows a high degree of anonymity, making it an ideal choice for people looking to avoid detection or surveillance.

Leaders like Richard Spencer, who is credited with coining the term “alt-right,” and Andrew Anglin, the editor of the neo-Nazi website The Daily Stormer, used Discord to discuss current events and debate movement strategy.

“It’s become a central communication interface for the white nationalist and neo-Nazi movements,” said Keegan Hankes, an analyst with the Southern Poverty Law Center, a nonprofit that studies right-wing extremist groups.

Reached after Discord’s decision to ban alt-right groups, Mr. Elman said, “I believe every communication channel — public or private — has a responsibility to investigate and take action on any reports of misuse including harassment, inciting violence or hate, and other abuse.”