Any board out there is full of posts with broken quotes and markup. I don't think BBCode works. It's widespread but it doesn't mean it works.
I otherwise agree with your points.
when it was born, it was convenient because it looked and acted like html while limiting the users ability fuck things up. at the same time it didn't go confusing the machine that was going to process it. it was clearly never designed for anything but bridging that gap... some 15+ years ago.
Flickr produces bbcode embeds, but imgur produces like 8 different embeds. existing adoption is not the sole mark of success for anything digital. facebook anyone?
the wysiwyg editors make it easier to generate "human usable code that limits fucking up". It matters because users can still fuck things up but for some reason they need to be able to read it.
THAT is why this type of thing should be used (on the developer level) as a replacement. It's easy to read, it's easy to grasp, it's consistent and it's no more difficult to parse (for erlang or haskell or php) at the server level than bbcode.
The best thing to replace that is markdown.
People don't really grok tags very well at all.
BBCode only works because of WYSIWYG editors that do the work for the user. That and the wide acceptance meaning that sites like Flickr produce BBCode embed statements.
Markdown works well for people just typing in plain text but still getting something formatted without trying to tag things.
If you have a WYSIWYG editor then who cares whether this is used... and as the embed stuff isn't compatible why pick this over BBCode?
If you don't have a WYSIWYG editor, and assuming you're in a web page and a textfield, then markdown works superbly well (ignoring the ugly image syntax).
I struggle to see, given the title and mention of BBCode, how the linked article overcomes any of the issues of the existing methods or offers any benefit.
Not to say that there isn't a place for this... but BBCode isn't it.