The story of Rumble’s success is instructive for both sides of the tense debate over balancing the right to free speech with the growing threat that disinformation poses to the stability of governments around the globe. For those who argue that Google and Facebook algorithms are blunt, deeply flawed instruments for policing discourse, Rumble offers a welcome alternative, albeit an imperfect one. And for those who fear that lawmakers and technology companies aren’t doing enough to tame false and fabricated information ahead of the next presidential election, Rumble has opened up a potentially dangerous loophole.

“There is something very significant about Rumble that I don’t think people appreciate,” said Angelo Carusone, president of Media Matters, the liberal media watchdog. Mr. Carusone said the painstaking work that went into persuading Facebook, Google and Twitter to be more aggressive about policing fake and inciting content prevented a lot of it from breaking through to a wider audience.

“Rumble basically changes that game,” he added.