I locked the door so that the Lie could not come in, but then the Truth whispered from behind the door: psst, hey how do i come in?
You dont want general chat because in your mind the majority of players are a bunch of freaks that will spam your head off.
You want to "lock them out" but by doing that you lock out all the helpful and enjoyable people out there.
An mmo is a community game, each community has people we like and people we dont like, we have to live with it, locking them out is not a solution.