As you say .. I may be something to fall back on.
But the Recovery tool we have been using works great.

I have a recovery on three separate flash drives for the three working Chromebooks we have here.

My old Acer c720 I use to play Flash Video Games.
My Wife's Asus Chromebook.
And my New Acer Chromebook 311, that is replacing two other Chromebooks that I beat to death.

Here is the link to download your very own.
It sits in your Extensions until you need it for your next new Chromebook.

https://chrome.google.com/webstore/detail/chromebook-recovery-utili/jndclpdbaamdhonoechobihbbiimdgai/RK%3D2/RS%3DUI2uA8SxDAwF_T9oPb4YviZFT3Y-