Looking at the site, it seems like MMD is Yet Another Markdown Implementation. Which is a good reason to participate, and they might have some particularly goo

Looking at the site, it seems like MMD is Yet Another Markdown Implementation. Which is a good reason to participate, and they might have some particularly good things to contribute (like a test suite), but it's not itself "standard Markdown". And even the test suite probably is overly specific and needs to be reviewed. For instance, it seems unlikely that balanced quotes would become a required feature (or at least to do so would require discussion).