I like this idea, I've had a thing or two I wanted to write on, but didn't want to setup a blog. I've actually thought of building something similar myself.
So, excited about this website, I clicked on "Write a post". Oh, you want to tie to my twitter account. Nevermind.
I plain old don't want to use my twitter account for this, or be forced to create a throwaway account on a completely unrelated service just to have a throwaway account for yours. And all because you can't be arsed to do any real auth, or allow users to post without accounts at all, which given the nature what you've built makes a whole, whole lot of sense. If I want to have to to make an account as a prerequisite to posting a one-off blogpost, I'll go get a blogger account.
I don't care if you promise a whole huggy bunch not to do anything with my twitter account. I don't trust you and I sure as hell don't trust your website's security.
So, excited about this website, I clicked on "Write a post". Oh, you want to tie to my twitter account. Nevermind.