My point is that those websites are just wrappers to ITA/Amadeus/Sabre and that is inherently unprofitable. Companies like Qatar Airlines are offering ZERO incentives to those kind of websites.
And why are they inherently unprofitable?Sites like Kayak, Skyscanner, Adioso are meta search sites only that make money by sending the user to another site to make a booking. They then make a small affiliate commission if the user then books their flight. Airlines actually really like good meta search sites because they acquire customers cheaply and avoid GDS fees altogether so are more likely to pay commission including your example of Qatar Airlines who pay 2% per booked flight to affiliates see http://www.qatarairways.com/ae/en/affiliates.page and not ZERO as you say. So they have zero need for the GDS unless an airline has no direct connect api in which case the GDS is that api source usually for availability (if you have implemented the schedules and fares locally) if not then a dumb search to the GDS is possible but a crap, slow, expensive way to include an airline in your site and no use to Adioso who need fast local graphed, cached data for expansive NLP searches.