When there's an event going on, the people that are good at events have to figure out the where the warper is, then go try to win. But when all these people are in one guild, only one person needs to actually know where the warper is, and everyone can still get in. It greatly increases their chances of winning, since they can get to the warper easier, which makes it harder for everybody else, since there are more event "pros" in events. Kinda unfair. Might as well not give any hints, and tell everybody the exact spot the warper is.