"Consolidator fares", where a travel agency buys up a large block of tickets for a flight at steep discount and resells them exclusively via their own channels are absolutely a thing, and have been for ages.

The catch is the travel agencies that do this are aiming for the absolute lowest total cost to stay competitive, and don't factor in overhead for trivial things like "customer support" in the price. And if something goes wrong, the airline will insist that you have to talk to your travel agency for help. So they can be a great deal as long as you're lucky enough to never have to call them due to irrops.)

As a general rule, this is why most frequent fliers insist that you should always book directly via the airline's website, even if it sometimes costs more.