It handles the more complex (e.g. CJK) input methods. The alternative is a hidden text field and you have to put more effort into emulating the cursor (e.g. up arrow/down arrow). Regularly re-generating the underlying markup removes a large class of edge cases and cross-browser incompatibilities in exchange for not being able to use the browser's native undo. It's still a lot harder than you'd expect but it seems to be working for draft and prosemirror better than my attempt to normalize the cross browser differences and rely on the browser.
P.S. I also came into this thread to endorse Prosemirror.
