I am a moron who didn't think that assumption through.
Turns out that plain-speak has been the norm for millenia. But during the Renaissance, there was a desire to return to high civility - to hierarchy - to nobility. But, this was an attempt at culture creation. Not the reality of the culture itself.
It's like your friends who still go to Rennaissance Fairs on the weekend. It's playing dress up. It's faking a British accent.
It wasn't real - even back then.