All I know is I booked a trip on aa.com and Travelocity simultaneously. Both came out with the same fare intially, then Travelocity tried to hit me for an additional 60 dollars when I went to the page to pay,saying the flight had just gone up.
Bought the same flight from aa.com for the original price. I wont use Travelocity ever again.
Once upon a time, the airline reservation system, called Sabre was what travel agents used to book flights. It was owned by American Airlines and they offered a command line interface that individuals could use to book flights on any airline. They would Fedex the tickets to you (paper tickets only in those days). I used it for years until the airlines started their own web site reservation systems.
And with Priceline... yeah you used to get a good price if you bid for it once but now it can be cheaper to just buy from the airline company. You can use travel aggregators to get an idea of how much you can save but beware any money savings can be quickly swallowed up by long airport changeovers. And then you’ll have to wonder if you still came out ahead as opposed to just flying non-stop to your destination.