There are a lot of people stuck in limbo and as someone who spent some time on a waitlist it isn’t fun. Hours can seem like eternities as you frantically refresh your application status online.
I am well aware of the hardships of being on the waitlist. I have been on one waitlist since January, and on two since March, and only got my first admits in May- so I've had my share of nerve wrecking wait. But you are making a good point about making someone else wait even longer. I guess it is also better to withdraw from a waitlist before they kick me out- at least I'll have some dignity left.