Twitter community notes are popular and pretty effective at calling out misleading information that has gone viral (organically or inorganically). I think writing off facts and arguments is premature.
Is that sort of stuff actually effective against propaganda though?
I'd assume that by the time a disclaimer is written up, submitted, and accepted according to whatever the criteria is, the original un-disclaimered message has been received and digested by its target audience.
There are a few things working in favor of community notes there
1. Viral tweets have a longer-than-average time window between the time they start to go viral and the time the median viewer sees them, so a community note can get there before the median viewer.
2. Users who interacted with a tweet before it got a community note will get a notification when the community note is added.
3. Community note writers can leave a note on a piece of media. If a tweet with a video gets a community note, and that note is about the video rather than about the tweet, that note will show on all other tweets that show that video.
Source: this excellent interview with the Community Notes team (https://asteriskmag.com/issues/08/the-making-of-community-no...), in the section that starts with "Asterisk: Another thing I wanted to talk about is speed". Really that whole interview is great, highlights how deliberate and thoughtful the Community Notes team was regarding everything about the feature. Which is, I think, why community notes have succeeded where a lot of previous fact-checking attempts have failed.
Plus, the propaganda also strongly paints fact checking as a mere ploy by other_team to try to cheat and win. So even if the community notes get to them, they will chalk it up to "liberals trying to hide the real truth."