I liked the article idea but I feel like it is two sort of related things in one. I'd have liked to learn more about why it's only one db. For instance because

I liked the article idea but I feel like it is two sort of related things in one. I'd have liked to learn more about why it's only one db. For instance because they're often insanely efficient and one server can handle many queries. I was also hoping that it'd suggest specific alternatives.