The emails have no unsubscribe link because they were sent directly from me, from my personal email account. There is no marketing mail list, which is why you have received 2 emails in total since you signed up almost a year ago.
The OAuth is there to enable us to continue building more features which will include using features only available using authenticated login. I am not sure why you have a particular dislike for this project but you have made it quite clear here, by email to me and in a previous HN post.
I am always open to understand what exactly your fears are about what we are doing - you have my email address.