IF they made sure that the same number of essentially identical LEDs were on at the same time. It's just not a good idea.
I don't think so. Even it perfectly matched, each LED would only get a share of the current fixed by the resistor, so they would be dimmer and dimmer as you turned on more LEDs.
It's amazing how many typed characters have been expended over the last couple of years here on people wishing to eliminate or reduce the number of resistors driving LEDs.
Lefty