Comment by KKPMW

Some of those things are addressed in my favourite markdown variant - multimarkdown https://fletcher.github.io/MultiMarkdown-6/MMD_Users_Guide.h...

The author has found a sweet spot between being very conservative with the original declarations and adding the missing functionality. It also comes with an amazing lightweight implementation written in C that behaves correctly: gets input from stdin or a file and passes it to stdout, without the -o flags that (e.g.) pandoc is using.