Potential thread drift, but why do we still get two, or more, boarding cards for two, or more, flights?
kL/AF, at least, gave you one piece of paper which covered all your connecting flights to your next stopping place.
Not only is that a convenience to passengers, in many ways, but I would imagine also helpful to gate/flight staff, in many other ways.
It's a real pity IATA is prohibited from making new standards like this, but that's not a reason for others to stick with outdated procedures.