That, plus a few crude buttons, is all this does. As several other comments point out, there's good reasons why real WYSIWYG packages are bigger—the user experience of working with a plain contentEditable element is still terrible, the output HTML still a complete mess. If you don't care much about that, you don't need an editor component, since setting an attribute and wiring up some buttons to call `execCommand` is easy enough to do from scratch.
Disclaimer: I work on one of those 'bloated' editors, http://prosemirror.net , and find it a little annoying when someone implies their crude afternoon hack is somehow equivalent and we're crazy for putting in all that effort.