Despite everything you said there, people already coordinate 48-person raids on discord in the form of Baldesion Arsenal and Delubrum Reginae (Savage). Everyone is not required to talk and they'd probably prefer most people to be quiet so the person doing callouts can be heard. If you have something to say, there are shout/alliance/party chats as well.
And people clear savage raids themselves without voice chatting. It's an option to reduce wipes a bit, but not exactly necessary.
