I was there when it was introduced. I've been playing WoW since 2005. As I said if they had LFG without CRZ then what is the issue ? We had rage quitters, ninja looters, unpleasant bastards back in vanilla, I personally never cared that much to go try to whip up people to blacklist them but I guess some would have if they read the forums (or listened to randos in general chat). Have to think it was added as Blizzard saw people using addons to do the same (probably the same with a lot of things, actually).
People talking about how good socializing was in Vanilla is really strange to me all I recall from my many PUG runs was immature jokes or just people bitching about my healing or the tank. A lot like LFG really. Certainly never recalled instances of helping people out, other than "thotbot it <expletive>". Maybe is just that NA players are bigger **** ?