No one does that except for people believing it’s a thing the upper class/nobility does. Which of course they don’t. Try to find video of the Nobel price dinner for example and see if any of the royalty poke their pinky out while drinking. Not that I’d worry about emulating those unelected sponges, but if there’s one thing they do know, it’s etiquette.
You’re right, it doesn’t contradict your statement and the middle/lower classes picking up on it may in fact have happened the way you described. I could have expressed that better. Sorry about that.