Don’t understand the need for a WYSIWYG editor in the first place. It’s not a word processor. The need to add formatting to a Slack message should be rare enough that the WYSIWYG overhead just isn’t worth it.
Very few non techy people know what markdown even is. (From my own experience asking friends etc.)
There is no step 2, that’s literally all you need to do.
That's not to say that I think we should be dumbing down software for them. In fact, we should be doing the exact opposite.
(There's a reason OpenBSD and macOS are both alive and well.)
AFAIK Facebook, Instagram, Snapchat, Twitter doesn't have a WYSIWYG editor.
Are there some hidden users that send font size 30 all capitals red colored text in Times New Roman to each other ?