Don't all younger Americans do this? Cutting food and pushing it onto the fork requires less dexterity than conveying it to one's mouth. I know Boomers who put down their knives after each cut (never using them to push) and swap their fork around before using it tines-down, and I think it's more comically affected than the tea–pinky thing.

Yes. For the record, Americans also don't wear their shoes indoors, except for maybe some people in extremely dry climates.