Each individual feed is exactly like that, I was missing though that you want cross-topic feeds. That might defeat the purpose of having a "Topic", which are designed more for new users to see what's available.

Although I believe that a "Feed" is exactly what you may be looking for, or at least my understanding of that. They are user customizable and even shareable, so you can put all the communities you want into such a feed and then load that. Politics, memes, art, history, news, you name it, including any topic areas you want and none that you do not, and then have a separate feed for like gaming, music, etc., maybe a third one for quiet reflections like poetry or whatever, and swap out whatever feed fits your current mood.

It takes a bit of doing - either to find an existing one that perfectly suits your desires, or rolling your own custom one, but I think that would scratch that itch?