Technically I didn’t have to resign; I just wasn’t going to write for his publications any longer, but I thought it best to explain to him why, and “resignation letter of sorts” is the easiest way to describe it.
I just felt as though he put a lot of effort into building a relationship with his writers — emails, phone calls, podcast invitations, comments, etc — and it’s very strange to me that he would literally block anyone who chooses not to continue to submit to his publications. There are plenty of other pubs on Medium (and elsewhere) that I might no longer work with, but never has the editor banned me from seeing anything else that they’ve written or published once the relationship has ended.