If you look at the browser dev tools, you can see that this operation removes the auto-generated paragraph and the section element and recreates a new paragraph. After that the RichText editor is barely usable:

• the focus block does not have the special style (dashed grey border)
• impossible to Publish or Save the content
• ...

Steps to reproduce

• create a content with a RichText field
• click in the RichText field without writing any thing
• Press Backspace