Thing is, if you double click a pdf to open it you’ll see it the way it should look, whereas in the case of markdown files you often get the raw characters. So on most stock systems this point is absolutely valid.

I guess it's a call for a OS-bundled markdown renderer but then you have to open different software depending on what you want to do with it which I'd hate personally

An editor with a function row to apply text styling, bullet points, … solves this problem. Basically the way the default Notes app on iOS (and I’d guess Android as well) already works, but saving as md instead.