Many of the practices in this field are mostly based on feelings and wishful thinking, rather than any demonstrable benefit. Part of the problem is that the tools are practically nondeterministic, and their results can't be compared reliably.

The other part is fueled by brand recognition and promotion, since everyone wants to make their own contribution with the least amount of effort, and coming up with silly Markdown formats is an easy way to do that.

EDIT: It's amusing how sensitive the blue-pilled crowd is when confronted with reality. :)