Once upon a time there was a 3.3.5a WoTLK private server I used to play on several years back (it's gone now) that had a population crest of 1.5k players, which was really decent by all accounts then. It was all by itself, not a part of a big group like Molten, and it had moderated global (but faction restricted) chat channels.
There was /world, /trade, /pvp, /lfg, and /help. The rules were simple. Players were to type about game related matters only of the appropriate sort in the correct channel. You didn't sell stuff in /lfg, and you didn't try to form pvp BG premade groups in /world. There was a /misc channel for all other matters which wasn't moderated.
It was really nice for a while. The GM's were hardcases about moderation. You got warnings, you got Mutes, and you got temp suspensions for being a problem child. A few got their accounts banned for 6 months (not perma) for being complete repeat offender asshats.
But then there was an influx of Serbians (WoWBeez server had closed) that screwed around in the channels SO hard that the GM's finally said "whatever" and grew tired of moderating children. The channels were closed, players were left to make their own channels if they really wanted, and City linked chats were left unmoderated.
GM's only have so much time to either moderate chat, or help players and test + fix bugs. Ask yourself what the quality of this player base is, and then ask if the GM's have the time to constantly wipe the asses of the players in the chat.
Good day.