This article actually helps support the use of this style. Read a different way, it essentially says a repository can become enormous before git starts to tap out. One obvious rule of thumb, is the linux kernel. If your code base is smaller than that, you are probably good.

At the same time, the pain that can come with the extreme over complexity of a code base with too granular a repository demarcation can be is phenomenal with git. It's complicated enough as is.