That's precisely the sort of distraction that this app forces you to ignore. Just insert something like <another word for crap that starts with e> and keep writing.
I've done pretty extensive writing on an IBM Selectric III typewriter because I love the mechanical sound of the machine. A lot of the fun comes from having a great pace and firing off letters and words to make a percussive noise. That said, I still often 'space out' when trying to collect my thoughts, sort of like in a trance while the machine hums at my fingertips. I like being able to take breaks to consider phrasing a word choice, which this app doesn't allow for at its root, which makes sense based on the type of 'push' the setup is more useful for in general.
For that reason alone - I would not be able to use this app too well.