I know a ton of people like this, generally the reason that is given is "I fly a bunch ofdifferent airlines and will never get anywhere (FF'wise) with any of them.

More commonly will be people that are into it with one carrier but do not bother to join other programmes (i.e. belong to BA and never join a Star programme even though they end op on SAS or BD 20 times a year).

That being said I do draw the line at hotel programmes. While I keep up with Hilton, I am not inclined to stay on top of several of them (saying that I do end up with a few Starwood points every year).

Then again I know the Chairman of a very LARGE European company (someone many may have heard of) a guy who often flies on the company jet and makes tens of millions a year (well with the current market conditions, who knows what the options are worth) who is RELIGIOUS about it, the guy will have his secretary speand an entire day chasing up misposted flights -- quite amazing!