I see that Discord generally isn't good enough for open communities. It's designed primary for private communications and thus a person with no access to a part

I see that Discord generally isn't good enough for open communities. It's designed primary for private communications and thus a person with no access to a particular server can't even read its contents (and sometimes one can't get access, like due a ban). Good old forums are much better. They are readable without even creating an account and they are also indexable by search engines.