I don't think Knuth would be happy with "Standard TeX". In my mind, the problematic part is of "Standard Markdown" is "Standard", not the composition of "X Mar

I don't think Knuth would be happy with "Standard TeX". In my mind, the problematic part is of "Standard Markdown" is "Standard", not the composition of "X Markdown". "Standard Markdown" makes it the real Markdown for most people, and that is the problem, that it feels like you're trying to steal the work from the original author, not build on it.