The book does say "Both orders are commonly used by modern processor types".
I'd say this sentence is quite misleading, since it would lead you to believe two falsehoods:
1. That both byte orders are equally prevalent in the wild, particularly in systems that are expected to run modern C code.
2. That both byte orders are equally likely to be found in "modern" (new or updated) processor design.
It's not entirely incorrect, but a better phrasing could be used to clarify that little-endian is the more modern and common storage order, but you still cannot ignore big-endian.
1. That both byte orders are equally prevalent in the wild, particularly in systems that are expected to run modern C code.
2. That both byte orders are equally likely to be found in "modern" (new or updated) processor design.
It's not entirely incorrect, but a better phrasing could be used to clarify that little-endian is the more modern and common storage order, but you still cannot ignore big-endian.