If you write Markdown in a way that your engine will misparse, you may well not notice—the compiler probably doesn’t even have the notion of throwing an error. The fact that you’re normally working with the unformatted text makes it even more likely that you won’t notice. (And the complexity is badly encapsulated, too.)
I have seen errors due to Markdown complexity so often. I just dealt with a blog where some images were completely missing because they’d written <img> tags in order to add some class attributes, and the engine didn’t allow raw HTML, and they didn’t notice they were gone (probably because ![]() images were still there). Markdown is so technically unsound it’s sometimes quite distressing.
We’re not talking about a table being off by a few pixels. We’re talking about words being mangled, text disappearing, much more severe stuff. Markdown isn’t even capable of table stuff.