Comment by gucci-on-fleek

KaTeX and MathJax aren't really the same as (La)TeX at all though---they support the same math syntax, but LaTeX is a complete document processing system while KaTeX is just a math renderer.

KaTeX + Markdown is comparable to LaTeX, in the same way that notepad.exe is comparable to an IDE---they both do the same thing, but one has 1000× as many features as the other. I'm personally biased towards LaTeX, but simpler solutions like Markdown certainly have their place.