Reddit's Markdown flavor is a bit weird though. It got closer to CommonMark with New Reddit, but the rest of the UI got worse, and people using Old Reddit don't get the formatting the new version supports, so things like code blocks are often broken.
Original Markdown didn’t have fenced code blocks either.
Yes, Old Reddit Markdown is much closer to original Markdown than to CommonMark. New Reddit Markdown is closer to CommonMark.