The idea that global chat is destined to be full of spammers is patently false. It doesn’t even need to be moderated. All we need is a user-defined set of filters. This makes it so you can auto ignore anyone who uses a certain phrase, and they will never know what the phrase was or that they are ignored. Their other accounts see the spam in full.
To prevent catching legitimate users in the block, you pick a unique phrase, the garbled web address they use to avoid global filters. The spammer doesn’t know that “fr33 r0bu.x” is what’s getting them ignored, because only you know what’s in your block list. Don’t want to see political discussion or dumb jokes either? Put the President in there, along with ol’ Chuck and Mankirk.
This isn’t some wild idea. We had exactly this system on IRC a quarter century ago, in addon scripts written by teenagers.