Who bans Zilean? when he have 4.5% pick ratio

Just started playing ranked games on my new acc , I main zilean sup so i bought him and his runes only because of less ips couldnt buy any other champ which i main

in champ select i declared Zilean as a support but my adc Banned him and when i asked him why did he? he said he had a zilean feeder last champ select

I have 0 idea why would someone ban zilean when he have 4.5% pick ratio and if u have doubt that the same zilean is in ur team .. cant u just look up for names? i had to play champ that was my 1st time playing and that game really sucked

cant expect anyone to play good when he cant even pick and ban rite