The fact that most of the big names (BA, Easyjet, Flybe, Aer Lingus, Virgin Atlantic) now have their own schemes may have cottoned on. Prospective candidates are probably thinking "why would I want to go in untagged at the back of the queue when I can go in on a tagged scheme".
Of course, I imagine that some of these airlines may well recruit untagged folk but I doubt they'd reveal their anticipated future numbers.
Re: Parson's point, subbies can make crazy amounts of money, I know of at least one self employed IT contractor at my gliding club for whom money would appear to not be limiting, he certainly was looking at buying an Open Class machine.