TDs are allowed to use 888 for players who leave a tournament without giving the TD notice. Generally, using an 888 for that sort of thing is reserved for players who finish one round and then disappear before the start of the next round. If they notify the TD, he can pull the player from the scoreboard and regroup players accordingly rather than run the risk of having a group that is short a player and can't continue (threesome becoming a twosome).
Frankly, I think anything that will lead players to being a bit more courteous toward the TD and at least make them give notice, if not a reason for quitting the tournament is a good thing in the long run. And I think that's part of the intent behind the creation of the 888 code.
Especially when we're talking a full tournament with a wait list, players quitting for reasons other than injury or emergency just plain suck and frankly, deserve some sort of reprimand. It really bothers me to see people quit because they're playing poorly or not having fun when there are people who'd love to be in the tournament no matter how well or poorly they might play but can't because they were beaten to the sign-ups by the quitter(s). If you are going to sign up for a tournament, stick it out or don't bother signing up at all.