4.4 kitkat - Why is there no option for USB INTERNET in WIRELESS & NETWORK SETTINGS on my Nexus 5?

I own a Nexus 5 with Android KitKat 4.4.2. I have been trying to do reverse tethering without root as is supposedly possible from Settings → Wireless & Networks → More → USB Internet. But I can't see any USB Internet option in Wireless & Networks. Why not ??

Can someone assist me with this ? I am having a PC with Windows XP.