No because you compose in one window and you see it in another. WYSIWYG means there is just one window and it correctly displays however the end result will be. Like using Word. It just isn't the same thing.
Split window + live preview is presumably much easier to program and requires less resources. It is perfectly serviceable in some situations. But for working with complicated documents: tables, images, nested lists, long URLs etc, a WYSIWYG editor is the best choice.
I'm not sure if it's impossible to create a proper WYSIWYG editor without electron or just nobody has bothered.
WYSIWYG means there is just one window and it correctly displays however the end result will be. Like using Word.
The only thing WYSIWYG means is "what you see is what you get". If you have a live preview you see what you get. *shrug*
Anyway, I'm pretty sure I have seen an editor that does it in a single pane, but couldn't recall the name of it right now for the life of me. Also not sure if it used Electron...
Split window + live preview is presumably much easier to program
Yes, obviously. It's actually so simple that I once built this myself in a few hours, with a bit of Qt and a call to pandoc. You can skip building, saving, and updating an abstract syntax tree, as well as expanding the nodes the cursor is in to the markdown source, which is a whole lot of complexity.
I’m not sure if it’s impossible to create a proper WYSIWYG editor without electron or just nobody has bothered.
Of course it's possible. But by now there are like hundreds of markdown editors around, so the problem will be finding the one that meets your specifications between the avalanche of those which don't.
In computing, WYSIWYG (/ˈwɪziwɪɡ/ WIZ-ee-wig), an acronym for What You See Is What You Get,[1] refers to software which allows content to be edited in a form that resembles its appearance when printed or displayed as a finished product,[2] such as a printed document, web page, or slide presentation. ... In general, WYSIWYG implies the ability to directly manipulate the layout of a document without having to type or remember names of layout commands.[4]
History
Before the adoption of WYSIWYG techniques, ... Users were required to enter special non-printing control codes (now referred to as markup code tags) to indicate that some text should be in boldface, italics, or a different typeface or size.
It doesn't seem to exist. I think the best way would be to make a very robust syntax highlighting but you'd have to go beyond what they can already do for change in text size, hiding elements, adding links, etc.