Emacs supports both RTL and math rendering (and not just in preview but inline too). I think this kind of flexibility is part of what is driving the popularity

Emacs supports both RTL and math rendering (and not just in preview but inline too). I think this kind of flexibility is part of what is driving the popularity of plaintext… there are dozens of modern web apps for everything, but if you need an idiosyncratic combination of features, old-school tools are sometimes one of the better options.