From my experience from pulling weeds on the farm, I can tell you that it would be very hard for any device to work as well as hands. You can tell when the weed is about to break when you have tactile contact, not with a metal device. Breaking the weed off is as bad as cutting it. It'll just sprout and grow back.
A hoe can come very, very close to mimicking the work of the hands -- especially when used by a pro. I agree that seedlings are best weeded by hand (this was my chore) but everything else gets the hoe or cultivator.
yeah but before it sprouts back up it digs its roots in deeper, making it harder to pull out next time around.