I agree with you Shamrock. I regularly see overbooked KLM flights at work, if I had booked a seat on the flight and paid for a ticket, and had somewhere to go, I would be really frustrated if the airline told me I couldn’t then travel on that flight, even if I were to be booked on the next flight or a flight out of a nearby airport.
Another annoying thing is, with the advent of internet check in, you can be offloading pax who could travel when the internet pax don’t turn up. But you can’t offload the internet check in until just before departure because as far as we know, they could be fully intending to travel!