Draft (http://draftin.com) has had a similar "Hemingway Mode" feature for a few months now.
It's potentially more useful, though, because when you're done "no backspace" writing, you can switch to normal mode and get all the features of a full collaborative piece of software.
It's potentially more useful, though, because when you're done "no backspace" writing, you can switch to normal mode and get all the features of a full collaborative piece of software.