This is a great marketing move as it tries something that many people who are charged $/£/€/?50+ for an overweight kilogram will have muttered at checkin desks.

This is a great marketing move as it tries something that many people who are charged $/£/€/?50+ for an overweight kilogram will have muttered at checkin desks. The truth is that it doesn't work because the bag restrictions are there for reasons unrelated to the weight of passengers. Firstly there's the baggage handlers. Some airports charge the airlines extra for heavier bags so it's a way to discourage a charge to the airline. But far more than that, even in the olden days before most airlines charged for checked baggage, it's a great way to extract additional revenue from the customers in a context of it being the customers' fault.