Sounds simple, but I have yet to be on a flight where nobody misses the guidelines. There are always quite a few people "lost" and most of the time intentionally.
Even if we just start with the assumption that n% of people will misunderstand, it still strikes me as unlikely that the best algorithm will be the current one.
I think we have the next round of tests though. See how many people you need to randomly swap before Steffen is worse than back-to-front.
Also stand-by passengers and people who catch an earlier flight. It used to be that at least one airline (United?) would let you switch planes for free if you asked the gate attendant <10 minutes before door closing and they still had room, so you'd often end up with a few savvy travelers loitering around until the very end of boarding. This hasn't worked the last couple times I tried it - they charge a fee - but I still almost always ask and see what the options are if I get to the airport a couple hours before my scheduled flight and have only carry-on baggage. Once I even managed to switch a 1-stop to an earlier direct flight: I paid the $50 fee but it still ended up cheaper than buying the direct ticket up-front.
I think we have the next round of tests though. See how many people you need to randomly swap before Steffen is worse than back-to-front.