The additional config pulls in pre-compiled packages for kmods only.I agree, but it's easier for a newcomer to install a pre-compiled package.
Could be time to make a how-to on this.
You can see that pkgs are pulled in from different directory of official pkg repo (pkg.freebsd.org) in url line of the config.
Unfortunately, not all kmod ports are stated to be available, though.
Only sane-to-be-cross-compiled ones are stated to be available.