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.
EDIT: found out where I've read about it: [2]
[0]: https://www.overleaf.com/learn/latex/A_six-part_series%3A_Ho...