There is something oddly satisfying about calling someone out. Few things feel better than calling someone a liar and explaining exactly how you know they are a liar.
Maybe one of the only better feelings is when people do it online. That way it exists forever for the whole world to see. A screencap becomes a plaque commemorating the nonsense that was called out here.
I mean, sure. You don't get the satisfaction of seeing the liar shrivel up and crawl away, but that is a small price to pay for immortality, no?