I don't have any strong opinion about YAML (or YAML Front Matter), having never used it much, but at a glance it seems reasonable to focus on writing content in.
On a sidenote:
Sure, the YAML and Markdown specs could be more strict but right now browsers are very tolerant of malformed HTML.
This wouldn't be possible without an extremely well-defined HTML spec :) For example, if I write the following in a hypothetical browser-parsed Markdown document:
_Hello!_
*Hello!*
**Hello!**
Which one should show up as bold? What about italic? Which one should just be surrounded by {1,2} asterisks?
Conversely, if I have:
<ul>
<li>Hello</li>
<li>World!
</ul>
Many browsers can determine (non-trivially, and not always, granted) that there's an unclosed `<li>` tag inside a closed `<ul>` environment and work with that. It's generally a different class of problems, though.
Note that <li> example is perfectly valid, and will be parsed correctly by any html5 capable parser. Per the html5 spec, the closing tag on an <li> element is optional.[0]
An li element's end tag may be omitted if the li element is immediately followed by another li element or if there is no more content in the parent element.
No, you can write the entire list without any </li> tags and it's perfectly fine. You also generally don't need to close your <p> tags to start a new paragraph, because paragraphs don't nest inside each other.
First two lines are italic, last one is bold. I'm not sure the point you are making, as all three are straightforward examples of unambiguous Markdown. (There are plenty of ambiguous cases you could have picked...)
> Though we understand many people would love to use Markdown in Slack messages, we have no plans to support it. Our message formatting is similar to other popular services like Skype and Google Talk, and is intended for a majority of our users who are unfamiliar with Markdown. However, we'll keep it in mind for the future.
On a sidenote:
This wouldn't be possible without an extremely well-defined HTML spec :) For example, if I write the following in a hypothetical browser-parsed Markdown document: Which one should show up as bold? What about italic? Which one should just be surrounded by {1,2} asterisks?Conversely, if I have:
Many browsers can determine (non-trivially, and not always, granted) that there's an unclosed `<li>` tag inside a closed `<ul>` environment and work with that. It's generally a different class of problems, though.