I'm not sure the selling point is similarity with markdown, but rather, to improve, or modernize LaTeX/TeX-the-language/s: TeX is really archaic: if you're curious, there's a series of articles by overleaf[0] detailing some of TeX's inner-working, quite insightful.
I remember reading — but can't find a source at the moment — that TeX originally didn't had counters; people came to rely on Church numerals[1] instead, before Knuth finally implemented them.