There are some magazines with no listed tags, and I haven't worked out how they choose the posts in their microblog tab.
The lead dev said they're trying to get better documentation done, but I'm guessing they've also got a lot of firefighting to do due to the reddit implosion.
One account should be enough for appearing on a magazine's microblog section. You would need a Kbin account to start a new thread in the threads section though.