I don’t understand your attitude. Just as you give your argument, I present mine as well.
Markdown is a formatting tool, and just like I can—but don’t want to—understand Microsoft’s .docx xml, I don’t want it to be mandatory to regularly work in markdown (but would like to retain compatibility). Mainly because it’s tiresome. I just want to type, and I’m a visual person, preferring buttons instead of complex formatting syntax. Which doesn’t mean there shouldn’t be a separate markdown editor for those that want it, like you.
Regarding your second question, I could as well ask why don’t you use Typora, then. The reason why I believe there should be a standard text editor is because I want to keep everything in one place, and not jump around between programs. But you, unlike me, already have got a pretty good markdown editor (that can, of course, be improved). Why have another quasi one?
Regarding the third comment, I don’t think the idea of WYSIWYG is a quasi-typora-like markdown-focused editor, but exactly a classic text editor that shows no markdown (while formatting everything in markdown, html, or whatever else in the background).
In short, I am focused on the content creation itself, and don’t want formatting to get in the way or present any significant amount of friction.