I strongly dislike flexible input like __Unambiguous___, *Unambiguous*
I’m reminded of the time Microsoft allowed mistakes in html writing. They attempted to parse a wide variety of common user errors. The effect of this was no standard and nobody else able to write a Microsoft compatible parser.
I dislike Nim lang because of this. At least Nim defined the specification. Still though I think it creates more cognitive load learning every legal variation and it makes searching more difficult.
I think to authors point if Markdown actually had a strict simple definition with one way to do it and no embedded html we would be better off.