As you follow the various sections in the book, you will observe that the book includes various patches that are required for a successful and secure installation of the packages. The general policy of the book is to include patches that fall in one of the following criteria:
Fixes a compilation problem.
Fixes a security problem.
Fixes a broken functionality.
In short, the book only includes patches that are either required or recommended. There is a Patches subproject which hosts various patches (including the patches referenced in the books) to enable you to configure your LFS the way you like it.