Preface: Not trying to be picky or anything, just a cheap suggestion. My suggestion was to add global "chat-moderators." Essentially what they'll do is moderate the chat and only have some commands. Suggestion: Chat Mods. Chat Mods are moderators that moderate the chat and prevent spammers, advertisers, ect. They will only have simple commands as: /kick. /mute. /ban. <- Must be an extremely good reason. /tempban. and maybe a few more. They'll receive a tag called "Chat-Mod" and in-game a tag something like: [Chat-Mod]
I understand what you are trying to suggest here, but I don't see this becoming a thing, only because the current moderators are moderating via the chat also. So, in other terms, they are kind of chat mods anyway. I am still going to stay neutral, however. I think if this was added, then it could probably help the server even more than it has already. Fair suggestion, we shall see what happens.
Maybe you should remove Ban and Tempban and if they see someone excessively violating the rules after many warnings, they can report it to a mod and they can ban them :D
Though there's a lot of hackers and they won't be able to help get rid of them. People will get pretty pissed off that a moderator cannot help them because they are only allowed to deal with chat offenses.