That's also a common fictional phrase. What if it's part of a blog post that's a combination of fiction and non-fiction. Or it's quoting somebody, and that person in the blog post is wrong, but since it's a direct quote, it would also be untrue to change it? Or if it was true that there were no clouds in the sky when it was written at 9 AM but there were clouds at 2 PM and you don't know when the blog post was written?

And how do you account for metaphors, common fictional phrases and uses, in-jokes, and claims that cannot be verified but a person still has the right to make? For example, I have a lot of Web memories that pre-date the Internet Archive and Wayback. I'm not pulling my claims from nowhere, but it's not my fault they're hard to back up either.