I covered that above. Don't pretend you don't know how it works.
I'll break this down for you using 19 as an example
Base ilvl for gear at 19 is 24, this means that any twink will have at LEAST 24 ilvl
With the white gear (neck and rings, no offhand) that goes up to 34 ilvl
That's 1% increase in base stats and depending on values for spells and spellpower coefficients thats a 3% damage increase on most casted spells, less on instant casts.
A full GFed twink such as Vianco's mage which is 45 ilvl (?) that's another 1% in stats and 3% damage increase over the 34ilvl dude, 5-6% over a dude in base ilvl gear in quest gear
Do you want me to break down the population of each increment?
>3% will have an item level of 20-24, everyone knows about vendor gear and can easily obtain it
82-90% will have an item level of 30-37, these are the dudes with full 24 gear or 27 bg gear, possibly a few GFed pieces or invasion gear and white vendor gear.
7-15% will have an item level of 40+, these are the guys who were around for the invasion event and have white vendor gear, these are the twinks who put in the time and effort to fully bis their twinks since they made them, some even with GFed gear from over 5 years ago
Every day the average of 34 ilvl is going up in terms of population, there will soon be a time where everyone except 1% of twinks have 34 ilvl.
Tell me again how there is a noticeable gear difference?
You seem to be confusing people with empty slots and a gear difference.
TL;DR - there's no gear difference between twinks and this idiot is wondering why a naked leveller is doing no damage in bgs, blaming blizzard.