The person next to you may have just walked on board and sat down, While your 22kg checked baggage has had to be processed by maybe 2 to 3 people passed though security transported to the aircraft loaded into the hold.
So what? Do you know how much extra fuel a couple of dozen grossly overweight pax per flight costs the airline per day? Why should the rest subsidise them? Perhaps fares should be based on the individual's weight!