[njr123]

You're assuming you would never want to use the same markdown on different sites. As soon as that happens you discover all sorts of weird cases and ambiguities.

I don't think this standardization is meant to stop sites from adding their own extensions, it is to make sure that the core markdown always looks the same, no matter which site/parser is being used.

[kuon]

Actually I think there are some reason to have slightly different markdown flavors depending of the context. Take the "indent 4spaces for code" thing, on a social website this might have a completely different meaning.

You will say, OK then, but this is not markdown, you'd be right, it'd be some markdown inspired markup, and that's my point, this specification might be relevant to github, and it is, but don't call it standard markdown, call it anything else.

Markdown wasn't designed for the purpose "standard markdown" is giving to it now. Alright, do something new, get traction, but putting markdown in a box doesn't seem to be the best approach to me.

[pimlottc]

There's room for extensions, but as for base functionality, I for one do not enjoy trying to remember whether a given site uses [links](http://like.this) or [links|http://like.this] or preformatted text ``like this`` or {{like this}} or <pre>like this</pre>...