We actually do have a basic Wysiwyg editor on HiveBlog.
On the top right corner of the post editing area, there is a great link saying Editor. Click on it and click in the editing area, you will see a mini Wysiwyg menu showing up.
Select a text and you will see more menu.
Once you start using the Wysiwyg editor, you can also switch to view the Raw HTML by clicking its link on the same top right corner of the text area.
It was added quickly by the Steemit Inc devs when doing the Communities feature and it's kind of an unknown feature as I don't think anyone has announced it yet.