Why Don’t All Phones Have This Clever PIN Code Scrambler?

[1] CyanogenMod operating system manufactured “Scramble PIN Layout”.

[2] It is a technique on how to use your keypad when you unlock your phone in order to privatize your keystrokes and pin.

[3] CyanogenMod is a modified version of Android that you need to install if you want your pin to be a secret.

[Source] http://www.gizmodo.com.au/2014/11/why-dont-all-phones-have-this-clever-pin-code-scrambler/