[osxrand]

The bit you quoted doesn't contradict what the OP stated, if /usr/local _does not_ exist, not even root can create it.

If it exists, we can use it as before.

Considering how many times I've installed OS X, I can't recall if /usr/local is there by default (excluding 10.11 for the moment). Will have to do another few installs and check.

[msbarnett]

I can confirm that /usr/local is there by default on a clean install of El Capitan

[dpatriarche]

On my Yosemite system /usr/local was created by default when the OS was installed.