The point of not building GA is because you aren't supposed to built selfish as a support and you won't get focused anyway in the first place/ if not out of position. The only selfish item I can think of you might probably build is Banshee's Veil but as a support you sometimes need to die to make sure you carries can kill all the opponents. The importance of an AD Carry living is more important than you living because you aren't the one dealing the damage and taking down objectives. You can rather help your carry by building something like Mikael's Blessing or Randuin's Omen depending on the situation. GA's build path is kinda poor and it just provides flat stats (excluding the passive). Btw, Gold Runes are outdated, you better go with Armor.

I tried this guide out today. The GA really did assist with the 360 noscoping. I landed so many 360 noscopes Faze Clan acccepted me.

This is really helpfull guide. Im winning more with this build