Big org-enthusiast here, but need to defend markdown. Plenty of folks have workflows that allow for inline execution in markdown. Babel is WAY more powerful, but markdown is fine for most code snippets.
#+call: something(foo=bar, list=baz[,0]) this level of features just does not exist in Markdown.
Just not what it was designed for.
The benefits of org and babel are precisely that you can do it in whatever language you’ve written the rest of your literate programming document.
As with most of these spectrums, markdown is less powerful and less complicated. Babel is one of the more confusing parts of org mode.