Part of the reason this is gettting attention right now is that its users added a note to a White House tweet that was accurate, informative, and so politically embarassing they deleted the tweet: https://news.ycombinator.com/item?id=33472161

This is a tad different from the previous approach which involved third-party fact checkers that were, uh, visibly slanted towards the Democrats to put it lightly (and whenever a non-Democrat-aligned news source got blessed as a fact checker by a masjor social media network there was a major media storm over it).