The italic text in Vim threw me for a loop. But I realised it makes sense.

Syntax highlighting already exists in editors. Terminal based ones often implement this in terms of terminal escapes or similar. Most modern terminal emulators support the enable-italic escape. Thus, some combination of these can effectively emulate markdown.

What I do note is that my root Linux consoles (Ctrl+Alt+F[1-6]), and LMDE) don’t support italics, suggesting the Vim instance is running in a full-screen terminal emulator under some windowing system or another.

That seems like overkill just for italics in an otherwise text-only interface, but maybe I’m missing something (patience being one possibility).