The author is completely missing the point of markdown.
"HTML can convey much richer information compared to markdown. It can of course do simple document structure like headers and formatting, but it can also represent all sorts of other information"
Yes exactly, and markdown is used when someone wants to just have raw text.
"HTML can convey much richer information compared to markdown. It can of course do simple document structure like headers and formatting, but it can also represent all sorts of other information"
Yes exactly, and markdown is used when someone wants to just have raw text.