GP may be referring to freakonomics. One of the things the authors point out is that it can actually be better for real estate brokers to crank out lots of sales rather than spend a lot of effort finding good deals for the seller.
In real estate brokers typically get around 2.5%, so even if they find a buyer that is ready to pay 100K more, it's only $2500 extra (so probably $1500 after taxes). It's not a lot of money esp if they can invest that time and energy in parallelizing other deals. Time is of the essence in such transactions.
And then of course a Buyer side agent's incentives are aligned exactly opposite to the buyer, but even if they would want to push for an early transaction above anything else.
