When well people learn? There is no such thing as a drop rate. There never was. Someone who's killed 1 vs someone who's killed 1000 has no less chance of getting a visage. There is no kill counter that decides "oh, you've killed X ammount, better give you a drop."
Yes, there is a drop rate. Do you honestly think that someone who's killed 1000 dragons has the same chance of a visage as one whose killed just one? I know some aspects require some math knowledge that not everyone has to have, but this really is just common sense.
There is a drop rate for everything, if we want to get theoretical, we can say every item has a drop rate to every monster. What is the drop rate of 3 noted dragon full helms from a goblin? one to infinity. What is the drop rate of bones from a chicken? 100% or one to one. Now, if you believe items don't have fixed percentages, that should mean every item is dropped at frequently as each other item. Obviously we don't come out of dust devil assignments with inventories full of dragon chains so that's not true.
However, there is some truth in what you said and that is that a person can kill one dragon and get a visage while another can kill 1000 and get nothing.
There ARE drop rates, but they are based on luck, not "count downs". There was an article released on tip.it VERY recently on this, it was a nice read.
Personally, I'd estimate somewhere between 1 in 2k - 1 in 5k.
I think you attacked him incorrectly.
Drop rates as used in this thread clearly refers to 1 in x kills.
These drop rates are pure myth.
The real drop rates to which you eluded are there when you make a kill you have a 1 in x chance of getting that drop and this doesn't not vary no matter how many you kill your chance of the drop is still 1 in x; where as the myth drop rates suggest as you kill more and don;t get the drop the rate slowly shifts from 1 in x to 1 in 1 or x in x