Just because it's part of the DMCA doesn't mean it is allowed to be used in a take-down notice. Or at the very least such a notice wouldn't have to be construed as such. At least that's what I understood from this article: https://news.ycombinator.com/item?id=24888234

And while formatting is somewhat irrelevant from a legal standpoint it is still one of the tools Github uses to ensure that their take-down requests contain all the required information. Acting upon a request that doesn't conform to the format is risky.