[philstu]

It depends which bit you're talking about.

A lot of implementations in various languages go with static regex approaches, which is a bit shit. This uses an AST which helps out a lot.

By adding the customization elements, people can write "GitHub Tables" or any sort of other extra syntax in.

And by keeping the HTML Rendering separate from the parsing process, other PDF renderers or whatever else could be added.

Somebody could make a [Maruka](http://markua.org/) extension for example, which is just CommonMark + Extra tags + PDF / eBook / etc.

It's not madness, and it will be optimized over time. Fear not. :)