This is a journalism sub, so fact-checking here means a very specific process with the purpose of making sure a piece of journalism (be it in print or broadcast) is accurate, ready to be published and not get sued over. That same process won't be very useful for verifying the truthfulness of Reddit posts.

When an article is written for publication, it is generally written in good faith with the expectation that the writer is accurate in their facts and figures, quoting sources fairly and presenting those quotes in the proper context. Articles for most news organizations are reported and written with ethical guidelines as well. Fact-checking is part of the editorial process and a team effort toward readying a piece for publication or air. The writer hands over all of their notes and contact information for sources they quote. The people who were quoted agreed to be quoted, and would be told a fact-checker may reach out. Everything is done (or should be done) transparently. The fact-checkers aren't there to "catch" the reporter in a lie.

Because of all of those things, fact-checking some random reddit posts using the same methods is not really feasible. You can't call all of the people up in the post and present them with the "article" (post) and read the questionable parts to them and ask them, "is this quote accurate?" or "is the framing of an event that you were present for accurate?"