Are there limits to how many Nations I can be a member of?
Yes. Currently, you can only be a member of 15 Nations - we may raise (or lower!) this number in the future.
This number is the sweet spot between bloat and tedium. 15 is enough for some broad Nations, some focused ones, and some that you administrate, if you so choose.
Choice becomes more important when you've got a limited number. Nation administrators are motivated to keep their Nation full of good content and good conversation, and readers and commenters benefit from that.