A part of that is probably once again protection against Patreon raising a fuss, or at least making it harder for them to. They don't like any 'official' content that breaks their terms being on linked sites like itch and the like so as long as it's 'fan-made' and hidden somewhere on discord it makes it harder for them to complain.I suppose that as long as you pay for the base game they give you the option to download it-get it somehow, but you don't get it in any way if you download it for free like through itch.io