"For example, they do not plan to add syntax highlighting blocks (the ```some code``` on GitHub) to their implementation, because they believe that it is outside the scope of markdown."
I guess many has changed since I last looked at CommonMark and perhaps the developers are pragmatic after all. I stand corrected and will try out their implementations now.
To correct the record, fenced code blocks have been there from the beginning: http://spec.commonmark.org/0.18/#fenced-code-blocks.