I think it is more a drip pricing scam to increase revenue for the airline, especially when it is for things that don't have an incremental cost for the airline. Can't compete with other airlines? No problem, advertise a lower price than your competitors, but then dream up things your competitor offers as included that almost ever customer wants (and perhaps even try to create problems for customers but charge to make them go away). Now you get customers in the door for the lower initial price, but almost all customers end up paying more than if they had just gone with the competitor.

It is not beneficial to the customer because it reduces the efficiency of the market (and hence competition) by making it harder to quickly compare prices and get the best overall offer.

Other industries do the same - insurers with exclusions, retailers trying to make warranties an optional extra (where regulations allow them to do it), ISPs trying to drip price extra charges.

If a business has absolute upfront honesty about all extra charges, but they genuinely have a reason to charge extra for some customers doing things that cost them significantly more, then that is a different matter, and not necessarily bad for their customers. But the second they try to conceal part of the price and progressively reveal it, it really is a form of scam.