I don't like WYSIWYG on the web. You do a long and tedious formatting of a forum post, then close the tab and it's all gone. I prefer to use a local text editor then Ctrl+V into web form. Which I can with markdown
I've seen this solved in some platforms with localstorage, so that it automatically saves your "draft" as you type and seamlessly restores it if you re-open the page. It was a really nice surprise the first time I experienced it (after closing a tab by mistake).
Check out Linear, I'm not affiliated, just yesterday I happened to close the dialog by misclicking and when I pressed create issue again there was the wall of text I wrote. My point is it's not a technical problem but a product one.
It depends for me. For my blog I have a web based editor, but one, that is just plain markdown with a preview. Similar to your described workflow.
For a note taking app I decided to use WYSIWYG because I don't have the space for a split view and didn't want to just look at the markdown as is.
My main gripe with WYSIWYG is that they can get in your way. When I create a verbatim block and can't leave that block anymore (looking at you Teams). I guess thats also why I enjoyed LaTeX as much as I did.