I would think that in this age of computers and fierce aviation competition, any airline that does not keep a comprehensive file on all its frequent flyers is a "bloody idiot". Having spent 15 years in the airline and travel business, and another 30 years since then running my own businesses, I am always amazed at how much money companies spend chasing new customers while at the same time they spend "sweet bugger all" keeping their existing ones happy! Part of keeping your existing ones happy is knowing their likes, dislikes, habits and quirks. When I was a Qantas Flight Steward in the late 60's, the Flight Passenger Manifest was a red (from memory) bi-fold folder with a slot for each seat on our Boeing 707's. There were ONLY two types of IMPORTANT people --- VIP's as in in Very Important People, normally pollies or royalty; and CIP's as in Commercially Important People, normally CEOs of BHP etc. I do not remember any category for Frequent Flyers, other than before-said CEO of BHP! Certainly, sales rep road warriors did not get a guernsey.
As one of the 50% of QF stewards of that time who was heterosexual, the most important role of the Passenger Manifest was not to identify Frequent Flyers. It existed solely to allow one to ascertain which of the little mini-skirted spunkies flying to London on Pacesetter fares was going to take their stopover at your own next crew stop. No damn good chatting someone up all the way from SYD to HKG only to find out they were not stopping over! Loves labours lost!
If you are a genuine FF, be thankful if your chosen airlines keep your details on their file. Unless you are a drunken anti-social yobbo, it can do you no harm.