Yes, and it clearly stated in the demo[1]. The key feature that this approach is trying to accomplish is allowing the user to not have to store anything beyond a password. Keeping track of a keyfile is HARD for a lay-user, so miniLock is trying to do the best it can securing files with only a password.
[1] - https://github.com/kaepora/miniLock/blob/master/src/index.ht...