Offline first, and what that buys
There is no account, no cloud and nothing watching you type. Quillard works with the wifi off because everything it does — the proofreader, dictation, search, export — runs on your machine.
The practical consequence is that nothing can be taken away from you. A service can change its terms, raise its price, or close; a file on your disk cannot.
No assistant in the writing room
Quillard will not write for you, finish your sentence, or suggest a better word. This is a decision, not a missing feature.
The argument for it is simple: the value of a first draft is that it is yours, including the parts that are wrong. A machine that smooths a sentence before you have finished thinking it takes something away that is hard to notice and harder to get back.
The argument against it is also real — plenty of writers find a suggestion useful precisely when they are stuck, and reasonable people disagree here. Quillard has taken a side, and you are entitled to want the other one.
Your copy has your name on it
Every licence is issued to a writer, and that name signs your tracked changes and your comments. When two machines are working on one book, you can tell whose hand a change is.
It is also why the app can be honest about collaboration without needing an account system: the name is in the licence, not in a database somewhere.