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.
Why thank you kind sir! Myself (primary dev) and the few people I know who use it agree :)
We've been intentionally quiet, to be honest. Lots of things to get straight since the initial release, much of which was done in 0.8. We're at a more stable point now and I hope to see some momentum build soon. Of course, any ideas you have would be welcome.
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.