Imagine an in person rally of 10k people. It would be a huge event both and get huge coverage. Bigger rallies will have even more. So some local media or local government has a chance to counter the falsehoods and make people aware. Governments may even choose to not allow some gatherings in some parts of the world if they fear they will cause a significant law and order issue.
Also, offline gatherings depend on people propagating the issue. This would have previously required people brain washed or dedicated for the cause. Now even normal people can forward anything to all theie WhatsApp contacts and boom, the chain goes on.
In Myanmar, as in most other cases, the government was an active belligerent; they wouldn't have been a check in any case. Genocides are usually conducted by groups that are already dominant in government, media, and society in general, so the kind of social institutions you point to are usually subverted before rallies (physical or virtual) directed imminently at violence occur.
So, it's quite unlikely that those institutions will check in-person rallies; more likely they will be organizing them and spreading their message.
People have little ability to change A, but could exert influence on companies to combat B if sufficient pressure were exerted...
[1] https://www.theatlantic.com/education/archive/2015/06/why-te...
Hypocrisy is an untenable position. Watching people argue that social media is equivalent to rallies, on HN would be funny if it weren’t so desperately sad. You can make this comment disappear, but you know I’m right about this. Even a brief glance through comment histories and submission histories bears it out.
Yeah, we've never had genocidal movements whose propaganda was spread, among other means, by in-person rallies or other such assemblies, precisely because “real world” gatherings have the kind of real time fact checking you discuss.